i18n: make warn_dangling_symref() automatically append \n

This helps remove \n from translatable strings

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -395,6 +395,7 @@ static int warn_if_dangling_symref(const char *refname, const unsigned char *sha
 		return 0;
 
 	fprintf(d->fp, d->msg_fmt, refname);
+	fputc('\n', d->fp);
 	return 0;
 }