Disable the GNUstep v2 ABI on Windows.

The code remains so that we can potentially reenable it in a point
release, but the driver will reject it.  Several issues were raised
during testing that made it clear that this was not quite ready for
general consumption.

Approved by: Hans Wennborg

git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_70@341354 91177308-0d34-0410-b5e6-96231b3b80d8

Author: David Chisnall

lib/Driver/ToolChains/Clang.cpp

@@ -4912,8 +4912,7 @@ ObjCRuntime Clang::AddObjCRuntimeArgs(const ArgList &args,
     }
     if ((runtime.getKind() == ObjCRuntime::GNUstep) &&
         (runtime.getVersion() >= VersionTuple(2, 0)))
-      if (!getToolChain().getTriple().isOSBinFormatELF() &&
-          !getToolChain().getTriple().isOSBinFormatCOFF()) {
+      if (!getToolChain().getTriple().isOSBinFormatELF()) {
         getToolChain().getDriver().Diag(
             diag::err_drv_gnustep_objc_runtime_incompatible_binary)
           << runtime.getVersion().getMajor();