[BUG] buffers: remove remains of wrong obsolete length check

A check was performed in buffer_replace2() to compare buffer
length with its read pointer. This has been wrong for a long
time, though it only has an impact when dealing with keep-alive
requests/responses. In theory this should be backported but
the check has no impact without keep-alive.

src/buffers.c

@@ -230,12 +230,6 @@ int buffer_replace2(struct buffer *b, char *pos, char *end, const char *str, int
 	if (delta + b->r >= b->data + b->size)
 		return 0;  /* no space left */
 
-	if (b->data + b->l < end) {
-		/* The data has been stolen, we could have crashed.
-		 * Maybe we should abort() ? */
-		return 0;
-	}
-
 	/* first, protect the end of the buffer */
 	memmove(end + delta, end, b->r - end);