compiler_wrapper: assume /dev/null is a configure test

Linux does a lot of "is this flag supported" testing by passing
/dev/null as an input file. Since this code is pretty heuristic-y
anyway, let's see if we can get by with calling that a `configure`-like
file. :)

BUG=None
TEST=emerge-eve chromeos-kernel-4_4; no more fatal warnings

Change-Id: Ie1cd80b36e93a9269280345a1df006baa356a9f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2142404
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
2 files changed