Fix static initialisation order fiasco issue for Version variables

Fixes a crash that could occur if the static constructor function for
the MainSettings.cpp TU happened to run before the variables in
Common/Version.cpp are initialised. (This is known as the static
initialisation order fiasco.)

By using wrapper functions, those variables are now guaranteed to be
constructed on first use.

Source/Core/Core/Core.cpp

@@ -982,7 +982,7 @@ void UpdateTitle(u32 ElapseTime)
     }
   }
 
-  std::string message = fmt::format("{} | {} | {}", Common::scm_rev_str, SSettings, SFPS);
+  std::string message = fmt::format("{} | {} | {}", Common::GetScmRevStr(), SSettings, SFPS);
   if (Config::Get(Config::MAIN_SHOW_ACTIVE_TITLE))
   {
     const std::string& title = SConfig::GetInstance().GetTitleDescription();