stripspace: fix outdated comment

The comment on top of stripspace() claims that the buffer
will no longer be NUL-terminated. However, this has not been
the case at least since the move to using strbuf in 2007.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/stripspace.c

@@ -22,8 +22,6 @@ static size_t cleanup(char *line, size_t len)
  * Remove empty lines from the beginning and end
  * and also trailing spaces from every line.
  *
- * Note that the buffer will not be NUL-terminated.
- *
  * Turn multiple consecutive empty lines between paragraphs
  * into just one empty line.
  *