Delete CC_Default and use the target default CC everywhere

Summary:
Makes functions with implicit calling convention compatible with
function types with a matching explicit calling convention.  This fixes
things like calls to qsort(), which has an explicit __cdecl attribute on
the comparator in Windows headers.

Clang will now infer the calling convention from the declarator.  There
are two cases when the CC must be adjusted during redeclaration:
1. When defining a non-inline static method.
2. When redeclaring a function with an implicit or mismatched
convention.

Fixes PR13457, and allows clang to compile CommandLine.cpp for the
Microsoft C++ ABI.

Excellent test cases provided by Alexander Zinenko!

Reviewers: rsmith

Differential Revision: http://llvm-reviews.chandlerc.com/D1231

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189412 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index b76bc2f..36aa289 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -196,8 +196,10 @@
                 SourceLocation ColonColonLoc, SourceLocation TildeLoc, 
                 PseudoDestructorTypeStorage DestroyedType)
   : Expr(CXXPseudoDestructorExprClass,
-         Context.getPointerType(Context.getFunctionType(Context.VoidTy, None,
-                                         FunctionProtoType::ExtProtoInfo())),
+         Context.getPointerType(Context.getFunctionType(
+             Context.VoidTy, None,
+             FunctionProtoType::ExtProtoInfo(
+                 Context.getDefaultCallingConvention(false, true)))),
          VK_RValue, OK_Ordinary,
          /*isTypeDependent=*/(Base->isTypeDependent() ||
            (DestroyedType.getTypeSourceInfo() &&