We add a simple cram test that `configure --help` works.
I added the test to build/tests because I'm not sure where else it should go.
This test uncovers a few interesting things:
1) piping `./configure --help` to `head` directly causes a Python
traceback (presumably due to the pipe disappearing once N lines
have been read)
2) "checking for vcs source checkout" is printed for --help
3) It is printed twice (!!)
These will be addressed later. Establishing test coverage is
more important.
MozReview-Commit-ID: 9zQ5X8ulTkc
--HG--
extra : rebase_source : aaf660152cdfe37580f559976bca13ea9bf14c49
Gregory Szorc