bump rename limit defaults

The current rename limit default of 100 was arbitrarily
chosen. Testing[1] has shown that on modern hardware, a
limit of 200 adds about a second of computation time, and a
limit of 500 adds about 5 seconds of computation time.

This patch bumps the default limit to 200 for viewing diffs,
and to 500 for performing a merge. The limit for generating
git-status templates is set independently; we bump it up to
200 here, as well, to match the diff limit.

[1]: See <20080211113516.GB6344@coredump.intra.peff.net>
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-merge-recursive.c

@@ -364,7 +364,7 @@ static struct path_list *get_renames(struct tree *tree,
 	opts.detect_rename = DIFF_DETECT_RENAME;
 	opts.rename_limit = merge_rename_limit >= 0 ? merge_rename_limit :
 			    diff_rename_limit >= 0 ? diff_rename_limit :
-			    100;
+			    500;
 	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 	if (diff_setup_done(&opts) < 0)
 		die("diff setup failed");

diff.c

@@ -19,7 +19,7 @@
 #endif
 
 static int diff_detect_rename_default;
-static int diff_rename_limit_default = 100;
+static int diff_rename_limit_default = 200;
 int diff_use_color_default = -1;
 static const char *external_diff_cmd_cfg;
 int diff_auto_refresh_index = 1;

wt-status.c

@@ -206,7 +206,7 @@ static void wt_status_print_updated(struct wt_status *s)
 	rev.diffopt.format_callback = wt_status_print_updated_cb;
 	rev.diffopt.format_callback_data = s;
 	rev.diffopt.detect_rename = 1;
-	rev.diffopt.rename_limit = 100;
+	rev.diffopt.rename_limit = 200;
 	rev.diffopt.break_opt = 0;
 	run_diff_index(&rev, 1);
 }