Limit test's triple in attempt to fix broken buildbot

Regression test for a target-independent bug keeps failing in the
Hexagon backend due to what appears an unrelated issue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297888 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed