Switch std::call_once to llvm::call_once

Summary:
The std::call_once implementation in libstdc++ has problems on few systems: NetBSD, OpenBSD and Linux PPC. LLVM ships with a homegrown implementation llvm::call_once to help on these platforms.

This change is required in the NetBSD LLDB port. std::call_once with libstdc++ results with crashing the debugger.

Sponsored by <The NetBSD Foundation>

Reviewers: labath, joerg, emaste, mehdi_amini, clayborg

Reviewed By: labath, clayborg

Subscribers: #lldb

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D29288

llvm-svn: 294202

lldb/source/Plugins/Language/Java/JavaLanguage.cpp

@@ -15,6 +15,7 @@
 
 // Other libraries and framework includes
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Threading.h"
 
 // Project includes
 #include "JavaFormatterFunctions.h"
@@ -64,10 +65,10 @@ bool JavaLanguage::IsNilReference(ValueObject &valobj) {
 }
 
 lldb::TypeCategoryImplSP JavaLanguage::GetFormatters() {
-  static std::once_flag g_initialize;
+  static llvm::once_flag g_initialize;
   static TypeCategoryImplSP g_category;
 
-  std::call_once(g_initialize, [this]() -> void {
+  llvm::call_once(g_initialize, [this]() -> void {
     DataVisualization::Categories::GetCategory(GetPluginName(), g_category);
     if (g_category) {
       llvm::StringRef array_regexp("^.*\\[\\]&?$");