Remove redundant bit clears from diff_setup()

All bits already clear after memset(0).
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

diff.c

@@ -2326,15 +2326,12 @@ void diff_setup(struct diff_options *options)
 	options->break_opt = -1;
 	options->rename_limit = -1;
 	options->dirstat_percent = 3;
-	DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
 	options->context = 3;
 
 	options->change = diff_change;
 	options->add_remove = diff_addremove;
 	if (diff_use_color_default > 0)
 		DIFF_OPT_SET(options, COLOR_DIFF);
-	else
-		DIFF_OPT_CLR(options, COLOR_DIFF);
 	options->detect_rename = diff_detect_rename_default;
 
 	if (!diff_mnemonic_prefix) {