Summary: Currently crash_test only puts data under /tmp. It is less flexible if we want to cover different file systems or media. Make crash_test to appreciate TEST_TMPDIR so that users can run it against another file system.
Test Plan: Run blackbox_crash_test and whitebox_crash_test with or without TEST_TMPDIR set and make sure DBs are put in the right place
Reviewers: kradhakrishnan, yhchiang, rven, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D43509