Good old GDTR singleton re-implemented via static local again, because previous implementation could cause undefined behavior as GDTR could be initialized after static type registrators that use it

libuavcan/include/uavcan/node/global_data_type_registry.hpp

@@ -64,12 +64,6 @@ private:
     mutable List srvs_;
     bool frozen_;
 
-    /**
-     * We can't use function local static variable for singleton because of code size issues:
-     *     http://stackoverflow.com/questions/22985570
-     */
-    static GlobalDataTypeRegistry singleton;
-
     GlobalDataTypeRegistry() : frozen_(false) { }
 
     List* selectList(DataTypeKind kind) const;

libuavcan/src/node/uc_global_data_type_registry.cpp

@@ -10,8 +10,6 @@
 namespace uavcan
 {
 
-GlobalDataTypeRegistry GlobalDataTypeRegistry::singleton;
-
 GlobalDataTypeRegistry::List* GlobalDataTypeRegistry::selectList(DataTypeKind kind) const
 {
     if (kind == DataTypeKindMessage)
@@ -129,6 +127,7 @@ GlobalDataTypeRegistry::RegistResult GlobalDataTypeRegistry::registImpl(Entry* d
 
 GlobalDataTypeRegistry& GlobalDataTypeRegistry::instance()
 {
+    static GlobalDataTypeRegistry singleton;
     return singleton;
 }