Disable the dwarf callsite attrs test on Windows

The Windows formats don't understand relocations inside of AT_return_pc.

  http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/270

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343888 91177308-0d34-0410-b5e6-96231b3b80d8

test/DebugInfo/X86/dwarf-callsite-related-attrs.ll

@@ -8,6 +8,10 @@
 ; }
 ; int __attribute__((disable_tail_calls)) main() { foo(); }
 
+; On Windows, we don't handle the relocations needed for AT_return_pc properly
+; and fail with "failed to compute relocation: IMAGE_REL_AMD64_ADDR32".
+; UNSUPPORTED: cygwin,windows-gnu,windows-msvc
+
 ; REQUIRES: object-emission
 ; RUN: %llc_dwarf < %s -o - | FileCheck %s -check-prefix=ASM
 ; RUN: %llc_dwarf < %s -filetype=obj -o %t.o