periodic_scheduler: allow test to work in out-of-tree builds

In order to speed up the init build, we want to enable out-of-tree
building.  Tweak the unittest to support that.

BUG=chromium:375989
TEST=`FEATURES=test emerge-amd64-generic chromeos-init` passes (out of tree)
TEST=`FEATURES=test emerge-amd64-generic chromeos-init` passes (in tree)
TEST=`./periodic_scheduler_unittest` passes

Change-Id: I7b66ce7194bd7b644b594c4e024a67356465a95f
Reviewed-on: https://chromium-review.googlesource.com/202000
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed