[Driver][test] Test intended target only

6fe7de90 changed GNU toolchain,
and added new RUN line to test expected behavior.

The change is for GNU toolchain only, so this will fail other toolchain,
eg: AIX.

Update the test with `-target` to test GNU tool chain only.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D99901