[task scheduler] Add push shortcuts to Makefile.
[task scheduler] Add push shortcuts to Makefile.

Copied from perf/Makefile.

BUG=skia:

Change-Id: Ie76b026acfe649f8d78b33506489068580f858bc
Reviewed-on: https://skia-review.googlesource.com/4778
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot