Simplify linkage code for static local vars.

The key insight here is that weak linkage for a static local variable
should always mean linkonce_odr, because every file that needs it will
generate a definition.  We don't actually care about the precise linkage
of the parent context.  I feel a bit silly that I didn't realize this before.

llvm-svn: 185381

clang/lib/CodeGen/CodeGenModule.cpp

@@ -515,11 +515,7 @@ void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
 
 llvm::GlobalValue::LinkageTypes
 CodeGenModule::getFunctionLinkage(GlobalDecl GD) {
-  return getFunctionLinkage(cast<FunctionDecl>(GD.getDecl()));
-}
-
-llvm::GlobalValue::LinkageTypes
-CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
+  const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
   GVALinkage Linkage = getContext().GetGVALinkageForFunction(D);
 
   if (Linkage == GVA_Internal)