[PATCH] Win64 ABI shouldn't extend integer type arguments.

[Reid Kleckner]

lgtm

For the record, mingw64 GCC does the same thing:

  _foobar:
        .seh_endprologue
        movzwl  %cx, %eax
        ret
        .seh_endproc

================
Comment at: test/CodeGen/2007-06-18-SextAttrAggregate.c:2
@@ -1,3 +1,3 @@
 // RUN: %clang_cc1 %s -o - -emit-llvm | FileCheck %s
-// XFAIL: aarch64, arm64
+// XFAIL: aarch64, arm64, x86_64-pc-win32
 
----------------
Let's just give this an explicit x86 triple.

http://reviews.llvm.org/D4380