fix ellipsis buffer overflow in xescape_full and utf8 escapers

src/basic/utf8.c

@@ -200,7 +200,8 @@ char* utf8_escape_non_printable_full(const char *str, size_t console_width, bool
         if (console_width == 0)
                 return strdup("");
 
-        p = s = prev_s = malloc(strlen(str) * 4 + 1);
+        size_t body = strlen(str) * 4;
+        p = s = prev_s = malloc(body + STRLEN("…") + 1);
         if (!p)
                 return NULL;