debug mode for unordered_map.  Also picked up a missing check and test in unordered_multimap.  This wraps up debug mode for the unordered containers.

llvm-svn: 187659
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 2f51de568f80d1b7992ddb4a43b7328c7fb965d6
diff --git a/include/__debug b/include/__debug
index 4c920a7..bac580c 100644
--- a/include/__debug
+++ b/include/__debug
@@ -24,6 +24,10 @@
 
 #if _LIBCPP_DEBUG_LEVEL >= 2
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 struct _LIBCPP_TYPE_VIS __c_node;