tests/cache_test: allow crossing mount points

When using an overlayfs system (like a Docker container), rmrf_local()
fails because part of the files to be removed are in different mount
points (layouts). And thus cache-test fails.

Letting crossing mount points is not a big problem, specially because
this is just for a test, not to be used in real code.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
(cherry picked from commit caa616ccc4384ea1479865e12b56cf816561a827)
1 file changed