Temporarily mark swiftasync unavailable for x86_64 Windows.

The new ABI needs stack adjustment, but on Windows, swifttailcc only
works if there is no stack adjustment.

Author: varungandhi-apple

clang/lib/Basic/Targets/X86.h

@@ -801,10 +801,11 @@ class LLVM_LIBRARY_VISIBILITY WindowsX86_64TargetInfo
     case CC_PreserveAll:
     case CC_X86_64SysV:
     case CC_Swift:
-    case CC_SwiftAsync:
     case CC_X86RegCall:
     case CC_OpenCLKernel:
       return CCCR_OK;
+    case CC_SwiftAsync:
+      return CCCR_Error;
     default:
       return CCCR_Warning;
     }

clang/test/CodeGen/swift-call-conv.c

@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -triple aarch64-unknown-windows-msvc -emit-llvm %s -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -emit-llvm %s -o - | FileCheck %s
 
 // REQUIRES: aarch64-registered-target,arm-registered-target,x86-registered-target
 

clang/test/Sema/attr-swiftcall.c

@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -triple x86_64-unknown-windows -fsyntax-only -verify %s
 
 #define SWIFTCALL __attribute__((swiftcall))
 #define SWIFTASYNCCALL __attribute__((swiftasynccall))