Skip --merge-order test when built with NO_OPENSSL
Skip --merge-order test when built with NO_OPENSSL

When built with NO_OPENSSL, rev-list --merge-order does not
work, causing t6001 test to fail.  Detect that and skip this
test to allow continuing to the rest of the tests.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

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