WX: Move init mutex lock to after command line

Calling std::exit while having a mutex locked leads to an assertion.

Moving the lock is fine, since all it protects against is really just
UICommon.

Source/Core/DolphinWX/Main.cpp

@@ -91,7 +91,6 @@ bool DolphinApp::OnCmdLineParsed(wxCmdLineParser& parser)
 
 bool DolphinApp::OnInit()
 {
-  std::lock_guard<std::mutex> lk(s_init_mutex);
   if (!wxApp::OnInit())
     return false;
 
@@ -110,6 +109,8 @@ bool DolphinApp::OnInit()
 
   ParseCommandLine();
 
+  std::lock_guard<std::mutex> lk(s_init_mutex);
+
   UICommon::SetUserDirectory(m_user_path.ToStdString());
   UICommon::CreateDirectories();
   InitLanguageSupport();  // The language setting is loaded from the user directory