commit: reorganise commit hint strings

Strings of hint messages inserted into editor on interactive commit was
scattered in-line, rendering the code harder to understand at first
glance.

Extract those messages out into separate variables to make the code
outline easier to follow.

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Signed-off-by: Hu Jialun <hujialun@comp.nus.edu.sg>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -889,6 +889,14 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		int ident_shown = 0;
 		int saved_color_setting;
 		struct ident_split ci, ai;
+		const char *hint_cleanup_all = _("Please enter the commit message for your changes."
+						 " Lines starting\nwith '%c' will be ignored,"
+						 " and an empty message aborts the commit.\n");
+		const char *hint_cleanup_space = _("Please enter the commit message for your changes."
+						   " Lines starting\n"
+						   "with '%c' will be kept; you may remove them"
+						   " yourself if you want to.\n"
+						   "An empty message aborts the commit.\n");
 
 		if (whence != FROM_COMMIT) {
 			if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS &&
@@ -911,20 +919,12 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 
 		fprintf(s->fp, "\n");
 		if (cleanup_mode == COMMIT_MSG_CLEANUP_ALL)
-			status_printf(s, GIT_COLOR_NORMAL,
-				_("Please enter the commit message for your changes."
-				  " Lines starting\nwith '%c' will be ignored, and an empty"
-				  " message aborts the commit.\n"), comment_line_char);
+			status_printf(s, GIT_COLOR_NORMAL, hint_cleanup_all, comment_line_char);
 		else if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS) {
 			if (whence == FROM_COMMIT && !merge_contains_scissors)
 				wt_status_add_cut_line(s->fp);
 		} else /* COMMIT_MSG_CLEANUP_SPACE, that is. */
-			status_printf(s, GIT_COLOR_NORMAL,
-				_("Please enter the commit message for your changes."
-				  " Lines starting\n"
-				  "with '%c' will be kept; you may remove them"
-				  " yourself if you want to.\n"
-				  "An empty message aborts the commit.\n"), comment_line_char);
+			status_printf(s, GIT_COLOR_NORMAL, hint_cleanup_space, comment_line_char);
 
 		/*
 		 * These should never fail because they come from our own