test: fix negative test case

Add missing -### to the driver to ensure that we dont try to run the
actual command.  The host may not support the IAS.  Should fix the SCEI
buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306123 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed