diff --no-index: don't leak buffers in queue_diff

queue_diff uses two strbufs, and at the end of the function
strbuf_reset was called.  This only reset the length of the buffer -
any allocated memory was leaked.  Using strbuf_release fixes this.

Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
Reviewed-by: René Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff-no-index.c

@@ -123,8 +123,8 @@ static int queue_diff(struct diff_options *o,
 		}
 		string_list_clear(&p1, 0);
 		string_list_clear(&p2, 0);
-		strbuf_reset(&buffer1);
-		strbuf_reset(&buffer2);
+		strbuf_release(&buffer1);
+		strbuf_release(&buffer2);
 
 		return ret;
 	} else {