clean up "static" and "constexpr" types

- use `static constexpr inline' to avoid requiring
  explicit declarations in object code
- use `const Foo* const' to maybe put into readonly
  binary segment (at least for ELF DSOs)
- `constexpr' in function scope has storage, avoid
  `static'
- don't use `constexpr' where there's no advantage,
  like arrays

We'd like to avoid overhead of atomic initialization
for each function call. No idea how `static constexpr'
requiring storage in the standard plays with atomic
initialization requirement. Hearsay points that
`constexpr' without `static' in block scope behaves
more to our liking. It's all hazy though.

I'm not 100% sure if `static inline constexpr' has any
storage. Hopefully none, like a #define, and stuff
bigger than registers gets coalesced within the same
module, with small stuff being immediates.

5 files changed, 58 insertions, 59 deletions

diff --git a/migration/20160906_00-mappings.cpp b/migration/20160906_00-mappings.cpp
index 0712afca..567fbdcb 100644
--- a/migration/20160906_00-mappings.cpp
+++ b/migration/20160906_00-mappings.cpp
@@ -20,7 +20,7 @@
 
 using namespace migrations;
 
-static const char* old_names[] =
+static const char* const old_names[] =
 {
     "tx", "tx_alt",
     "ty", "ty_alt",
@@ -30,7 +30,7 @@ static const char* old_names[] =
     "rz", "rz_alt",
 };
 
-static const char* new_names[] = {
+static const char* const new_names[] = {
     "spline-X",       "alt-spline-X",
     "spline-Y",       "alt-spline-Y",
     "spline-Z",       "alt-spline-Z",
diff --git a/migration/20160906_01-axis-signs.cpp b/migration/20160906_01-axis-signs.cpp
index 6dfa0d7c..7b0be70a 100644
--- a/migration/20160906_01-axis-signs.cpp
+++ b/migration/20160906_01-axis-signs.cpp
@@ -15,13 +15,18 @@
 using namespace options;
 using namespace migrations;
 
+const char* const axis_names[] =
+{
+    "yaw", "pitch", "roll",
+    "x", "y", "z",
+};
+
+const QString alt_sign_fmt = QStringLiteral("%1-alt-axis-sign");
+
 struct axis_signs_split_rc11 : migration
 {
     axis_signs_split_rc11() = default;
 
-    static const char* axis_names[6];
-    static const QString fmt;
-
     QString unique_date() const override
     {
         return "20160909_01";
@@ -32,47 +37,43 @@ struct axis_signs_split_rc11 : migration
         return "asymmetric axis option to other section";
     }
 
-    bool should_run() const override
+    bool should_run() const override;
+    void run() override;
+};
+
+OPENTRACK_MIGRATION(axis_signs_split_rc11);
+
+bool axis_signs_split_rc11::should_run() const
+{
+    bundle new_bundle = make_bundle("opentrack-mappings");
+    bundle old_bundle = make_bundle("opentrack-ui");
+
+    for (const char* name : axis_names)
     {
-        bundle new_bundle = make_bundle("opentrack-mappings");
-        bundle old_bundle = make_bundle("opentrack-ui");
-
-        for (const char* name : axis_names)
-        {
-            // new present, already applied
-            if (new_bundle->contains(fmt.arg(name)))
-                return false;
-        }
-
-        for (const char* name : axis_names)
-        {
-            // old present
-            if (old_bundle->contains(fmt.arg(name)))
-                return true;
-        }
-
-        // nothing to copy
-        return false;
+        // new present, already applied
+        if (new_bundle->contains(alt_sign_fmt.arg(name)))
+            return false;
     }
 
-    void run() override
+    for (const char* name : axis_names)
     {
-        bundle new_bundle = make_bundle("opentrack-mappings");
-        bundle old_bundle = make_bundle("opentrack-ui");
-
-        for (const char* name : axis_names)
-            new_bundle->store_kv(fmt.arg(name), QVariant(old_bundle->get<bool>(fmt.arg(name))));
-
-        new_bundle->save();
+        // old present
+        if (old_bundle->contains(alt_sign_fmt.arg(name)))
+            return true;
     }
-};
 
-const char* axis_signs_split_rc11::axis_names[] =
+    // nothing to copy
+    return false;
+}
+
+void axis_signs_split_rc11::run()
 {
-    "yaw", "pitch", "roll",
-    "x", "y", "z",
-};
+    bundle new_bundle = make_bundle("opentrack-mappings");
+    bundle old_bundle = make_bundle("opentrack-ui");
 
-const QString axis_signs_split_rc11::fmt = QStringLiteral("%1-alt-axis-sign");
+    for (const char* name : axis_names)
+        new_bundle->store_kv(alt_sign_fmt.arg(name),
+                             QVariant(old_bundle->get<bool>(alt_sign_fmt.arg(name))));
 
-OPENTRACK_MIGRATION(axis_signs_split_rc11);
+    new_bundle->save();
+}
diff --git a/migration/20160906_02-modules.cpp b/migration/20160906_02-modules.cpp
index 0f0951f1..9ce2b9dc 100644
--- a/migration/20160906_02-modules.cpp
+++ b/migration/20160906_02-modules.cpp
@@ -15,12 +15,17 @@
 using namespace options;
 using namespace migrations;
 
+static const char* const module_names[3] =
+{
+    "tracker-dll",
+    "protocol-dll",
+    "filter-dll",
+};
+
 struct split_modules_rc11 : migration
 {
     split_modules_rc11() = default;
 
-    static const char* names[3];
-
     QString unique_date() const override
     {
         return "20160909_02";
@@ -36,11 +41,11 @@ struct split_modules_rc11 : migration
         bundle new_bundle = make_bundle("modules");
         bundle old_bundle = make_bundle("opentrack-ui");
 
-        for (const char* name : names)
+        for (const char* name : module_names)
             if (new_bundle->contains(name))
                 return false;
 
-        for (const char* name : names)
+        for (const char* name : module_names)
             if (old_bundle->contains(name))
                 return true;
 
@@ -52,18 +57,11 @@ struct split_modules_rc11 : migration
         bundle new_bundle = make_bundle("modules");
         bundle old_bundle = make_bundle("opentrack-ui");
 
-        for (const char* name : names)
+        for (const char* name : module_names)
             new_bundle->store_kv(name, QVariant(old_bundle->get<QString>(name)));
 
         new_bundle->save();
     }
 };
 
-const char* split_modules_rc11::names[3] =
-{
-    "tracker-dll",
-    "protocol-dll",
-    "filter-dll",
-};
-
 OPENTRACK_MIGRATION(split_modules_rc11);
diff --git a/migration/20170420_00-udp-naming.cpp b/migration/20170420_00-udp-naming.cpp
index de4674bd..0361b7b9 100644
--- a/migration/20170420_00-udp-naming.cpp
+++ b/migration/20170420_00-udp-naming.cpp
@@ -13,11 +13,11 @@
 using namespace migrations;
 using namespace options;
 
-static constexpr const char* old_tracker_name = "UDP sender";
-static constexpr const char* old_proto_name = "UDP Tracker";
+static const char* const old_tracker_name = "UDP sender";
+static const char* const old_proto_name = "UDP Tracker";
 
-static constexpr const char* new_tracker_name = "UDP over network";
-static constexpr const char* new_proto_name = "UDP over network";
+static const char* const new_tracker_name = "UDP over network";
+static const char* const new_proto_name = "UDP over network";
 
 struct rename_udp_stuff : migration
 {
diff --git a/migration/20171013_00-tracker-pt-threshold.cpp b/migration/20171013_00-tracker-pt-threshold.cpp
index 32e69f6d..aab64de7 100644
--- a/migration/20171013_00-tracker-pt-threshold.cpp
+++ b/migration/20171013_00-tracker-pt-threshold.cpp
@@ -13,9 +13,9 @@
 using namespace options;
 using namespace migrations;
 
-static constexpr const char* old_name = "threshold-primary";
-static constexpr const char* new_name = "threshold-slider";
-static constexpr const char* bundle_name = "tracker-pt";
+static const char* const old_name = "threshold-primary";
+static const char* const new_name = "threshold-slider";
+static const char* const bundle_name = "tracker-pt";
 
 struct move_int_to_slider : migration
 {