Teach --stdin option to "log" family

Move the logic to read revs from standard input that rev-list knows about
from it to revision machinery, so that all the users of setup_revisions()
can feed the list of revs from the standard input when "--stdin" is used
on the command line.

Allow some users of the revision machinery that want different semantics
from the "--stdin" option to disable it by setting an option in the
rev_info structure.

This also cleans up the kludge made to bundle.c via cut and paste.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-blame.c

@@ -2352,6 +2352,7 @@ parse_done:
 			die_errno("cannot stat path '%s'", path);
 	}
 
+	revs.disable_stdin = 1;
 	setup_revisions(argc, argv, &revs, NULL);
 	memset(&sb, 0, sizeof(sb));