[MSVC Compat] Enable ABI impacting non-conforming behavior independently of -fms-compatibility

No ABI for C++ currently makes it possible to implement the standard
100% perfectly.  We wrongly hid some of our compatible behavior behind
-fms-compatibility instead of tying it to the compiler ABI.

llvm-svn: 249656

clang/lib/CodeGen/CodeGenModule.cpp

@@ -2386,7 +2386,7 @@ static bool isVarDeclStrongDefinition(const ASTContext &Context,
 
   // Declarations with a required alignment do not have common linakge in MSVC
   // mode.
-  if (Context.getLangOpts().MSVCCompat) {
+  if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
     if (D->hasAttr<AlignedAttr>())
       return true;
     QualType VarType = D->getType();