MINOR: channel/buffer: use c_realign_if_empty() instead of buffer_realign()

This patch removes buffer_realign() and replaces it with c_realign_if_empty()
instead.

include/common/buffer.h

@@ -394,15 +394,6 @@ static inline void bi_fast_delete(struct buffer *buf, int n)
 	buf->p += n;
 }
 
-/* Tries to realign the given buffer. */
-static inline void buffer_realign(struct buffer *buf)
-{
-	if (!(buf->i | buf->o)) {
-		/* let's realign the buffer to optimize I/O */
-		buf->p = buf->data;
-	}
-}
-
 /* Schedule all remaining buffer data to be sent. ->o is not touched if it
  * already covers those data. That permits doing a flush even after a forward,
  * although not recommended.

src/channel.c

@@ -91,7 +91,7 @@ int co_inject(struct channel *chn, const char *msg, int len)
 		return -2;
 	}
 
-	buffer_realign(chn->buf);
+	c_realign_if_empty(chn);
 	max = bo_contig_space(chn->buf);
 	if (len > max)
 		return max;

src/proto_http.c

@@ -8318,7 +8318,7 @@ void http_reset_txn(struct stream *s)
 		s->res.buf->i = 0;
 
 	/* Now we can realign the response buffer */
-	buffer_realign(s->res.buf);
+	c_realign_if_empty(&s->res);
 
 	s->req.rto = strm_fe(s)->timeout.client;
 	s->req.wto = TICK_ETERNITY;