strbuf: remove global variable

As a library that only interacts with other primitives, strbuf should
not utilize the comment_line_char global variable within its
functions. Therefore, add an additional parameter for functions that use
comment_line_char and refactor callers to pass it in instead.
strbuf_stripspace() removes the skip_comments boolean and checks if
comment_line_char is a non-NUL character to determine whether to skip
comments or not.

Signed-off-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/wt-status.c b/wt-status.c
index 068b76e..677465b 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -1024,7 +1024,7 @@ static void wt_longstatus_print_submodule_summary(struct wt_status *s, int uncom
 	if (s->display_comment_prefix) {
 		size_t len;
 		summary_content = strbuf_detach(&summary, &len);
-		strbuf_add_commented_lines(&summary, summary_content, len);
+		strbuf_add_commented_lines(&summary, summary_content, len, comment_line_char);
 		free(summary_content);
 	}
 
@@ -1099,8 +1099,8 @@ void wt_status_append_cut_line(struct strbuf *buf)
 {
 	const char *explanation = _("Do not modify or remove the line above.\nEverything below it will be ignored.");
 
-	strbuf_commented_addf(buf, "%s", cut_line);
-	strbuf_add_commented_lines(buf, explanation, strlen(explanation));
+	strbuf_commented_addf(buf, comment_line_char, "%s", cut_line);
+	strbuf_add_commented_lines(buf, explanation, strlen(explanation), comment_line_char);
 }
 
 void wt_status_add_cut_line(FILE *fp)