Merge pull request #123 from Teemperor/RevertLanguagesFlagNext

[upstreaming] Revert llvm::once_flag -> std::once_flag

Author: Teemperor

lldb/source/Target/Language.cpp

@@ -30,7 +30,7 @@ typedef std::map<lldb::LanguageType, LanguageUP> LanguagesMap;
 
 static LanguagesMap &GetLanguagesMap() {
   static LanguagesMap *g_map = nullptr;
-  static std::once_flag g_initialize;
+  static llvm::once_flag g_initialize;
 
   llvm::call_once(g_initialize, [] {
     g_map = new LanguagesMap(); // NOTE: INTENTIONAL LEAK due to global
@@ -41,7 +41,7 @@ static LanguagesMap &GetLanguagesMap() {
 }
 static std::mutex &GetLanguagesMutex() {
   static std::mutex *g_mutex = nullptr;
-  static std::once_flag g_initialize;
+  static llvm::once_flag g_initialize;
 
   llvm::call_once(g_initialize, [] {
     g_mutex = new std::mutex(); // NOTE: INTENTIONAL LEAK due to global