[llvm-config] Fix cflags test looking for "error"

This test is (I think) actually trying to make sure no errors are printed, but it hits on the string "error" in flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289484 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed