Add r180263 back, but fix hasBraces() to be correct during parsing.

Original commit message:

Fix a case in linkage computation that should check for single line extern "C".

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180591 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index c2b7513..0646499 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -1816,14 +1816,14 @@
                                          SourceLocation ExternLoc,
                                          SourceLocation LangLoc,
                                          LanguageIDs Lang,
-                                         SourceLocation RBraceLoc) {
-  return new (C) LinkageSpecDecl(DC, ExternLoc, LangLoc, Lang, RBraceLoc);
+                                         bool HasBraces) {
+  return new (C) LinkageSpecDecl(DC, ExternLoc, LangLoc, Lang, HasBraces);
 }
 
 LinkageSpecDecl *LinkageSpecDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(LinkageSpecDecl));
   return new (Mem) LinkageSpecDecl(0, SourceLocation(), SourceLocation(),
-                                   lang_c, SourceLocation());
+                                   lang_c, false);
 }
 
 void UsingDirectiveDecl::anchor() { }