Unsupport test that should not be run on Hexagon

llvm-svn: 255667
diff --git a/clang/test/CodeGen/ms_this.cpp b/clang/test/CodeGen/ms_this.cpp
index f3d8861..bc5f955 100644
--- a/clang/test/CodeGen/ms_this.cpp
+++ b/clang/test/CodeGen/ms_this.cpp
@@ -1,3 +1,7 @@
+// Hexagon build bot defines hexagon-unknown-elf as the default target triple,
+// which seems to trump the -triple argument for some reason.
+// UNSUPPORTED: hexagon
+
 // RUN: %clang_cc1 -triple x86_64-pc-win32 -fasm-blocks -emit-llvm %s -o - | FileCheck %s
 class t1 {
 public: