Add subtree test Makefile
Add subtree test Makefile

Add a Makefile to run subtree tests.  This is largely copied
from the standard test suite with irrelevant targets removed
and some paths altered to account for where subtree tests live.

Signed-off-by: David A. Greene <699889fa4d775c82b36574aaa0f8ebb772e0c366@obbligato.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git