Add ARM test for r227489, but XFAIL because this is actually more work than it appear...

Add ARM test for r227489, but XFAIL because this is actually more work than it appeared to be.

Also revert r227489 since it didn't actually fix the thing I thought I
was fixing (since the test case was targeting the wrong architecture
initially). The change might be correct & demonstrated by other test
cases, but it's not a priority for me to find those test cases right
now.

Filed PR22417 for the failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227632 91177308-0d34-0410-b5e6-96231b3b80d8