Temporarily xfail a test that breaks on OS X when building with LTO.

This is another case where internalize hides a symbol that is needed by
a loadable module.  I am currently investigating a proper fix but this patch
will get our buildbot to pass in the meantime. <rdar://problem/14578094>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187601 91177308-0d34-0410-b5e6-96231b3b80d8

test/Feature/load_module.ll

@@ -2,6 +2,7 @@
 ; RUN: opt < %s -load=%llvmshlibdir/LLVMHello%shlibext -hello \
 ; RUN:   -disable-output 2>&1 | grep Hello
 ; REQUIRES: loadable_module
+; XFAIL: lto_on_osx
 ; FIXME: On Cygming, it might fail without building LLVMHello manually.
 
 @junk = global i32 0