This patch allows users to use the short form -q on
log and format-patch, which was non possible before.

Also the documentation of format-patch mentions -q now.

The documentation of log doesn't even talk about --quiet, so I'll leave
that for more experienced git contributors. ;)
It doesn't seem to change the default behavior, but in combination
with --stat for example it suppresses the actual stats.
however the only relevant code in log is
	if (quiet)
		rev->diffopt.output_format |= DIFF_FORMAT_NO_OUTPUT;
Signed-off-by: NStefan Beller <stefanbeller@googlemail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>