submodule: display summary header in bold

Currently, 'git diff --submodule' displays output with a bold diff
header for non-submodules.  So this part is in bold:

    diff --git a/file1 b/file1
    index 30b2f6c..2638038 100644
    --- a/file1
    +++ b/file1

For submodules, the header looks like this:

    Submodule submodule1 012b072..248d0fd:

Unfortunately, it's easy to miss in the output because it's not bold.
Change this.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -2259,7 +2259,7 @@ static void builtin_diff(const char *name_a,
 		const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
 		show_submodule_summary(o->file, one ? one->path : two->path,
 				one->sha1, two->sha1, two->dirty_submodule,
-				del, add, reset);
+				meta, del, add, reset);
 		return;
 	}
 

submodule.c

@@ -258,7 +258,7 @@ int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
 
 void show_submodule_summary(FILE *f, const char *path,
 		unsigned char one[20], unsigned char two[20],
-		unsigned dirty_submodule,
+		unsigned dirty_submodule, const char *meta,
 		const char *del, const char *add, const char *reset)
 {
 	struct rev_info rev;
@@ -292,15 +292,15 @@ void show_submodule_summary(FILE *f, const char *path,
 		return;
 	}
 
-	strbuf_addf(&sb, "Submodule %s %s..", path,
+	strbuf_addf(&sb, "%sSubmodule %s %s..", meta, path,
 			find_unique_abbrev(one, DEFAULT_ABBREV));
 	if (!fast_backward && !fast_forward)
 		strbuf_addch(&sb, '.');
 	strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
 	if (message)
-		strbuf_addf(&sb, " %s\n", message);
+		strbuf_addf(&sb, " %s%s\n", message, reset);
 	else
-		strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
+		strbuf_addf(&sb, "%s:%s\n", fast_backward ? " (rewind)" : "", reset);
 	fwrite(sb.buf, sb.len, 1, f);
 
 	if (!message) {

submodule.h

@@ -20,7 +20,7 @@ void handle_ignore_submodules_arg(struct diff_options *diffopt, const char *);
 int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg);
 void show_submodule_summary(FILE *f, const char *path,
 		unsigned char one[20], unsigned char two[20],
-		unsigned dirty_submodule,
+		unsigned dirty_submodule, const char *meta,
 		const char *del, const char *add, const char *reset);
 void set_config_fetch_recurse_submodules(int value);
 void check_for_new_submodule_commits(unsigned char new_sha1[20]);