Fix diff-tree -s

setup_revisions() calls diff_setup_done() before we can set default
value for output_format.  Don't convert DIFF_FORMAT_NO_OUTPUT to 0 in
diff_setup_done(), it is useless and makes diff-tree believe no diff
format parameters were given and thus lets it reset output_format to
DIFF_FORMAT_RAW.

Signed-off-by: Timo Hirvonen <tihirvon@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff.c

@@ -1438,9 +1438,6 @@ int diff_setup_done(struct diff_options *options)
 	    (0 <= options->rename_limit && !options->detect_rename))
 		return -1;
 
-	if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
-		options->output_format = 0;
-
 	if (options->output_format & (DIFF_FORMAT_NAME |
 				      DIFF_FORMAT_NAME_STATUS |
 				      DIFF_FORMAT_CHECKDIFF |