Pass the special backend option to this test for now to get it passing
again.

This test should a) test IR or be moved, and b) get an actual option
for the dwarf pub sections.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189633 91177308-0d34-0410-b5e6-96231b3b80d8