diff-delta: use realloc instead of xrealloc

Commit 83572c1a91 changed many
realloc to xrealloc. This change was made in diff-delta.c too,
although the code can handle an out of memory failure.

This patch reverts this change in diff-delta.c.

Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff-delta.c

@@ -388,7 +388,7 @@ create_delta(const struct delta_index *index,
 				outsize = max_size + MAX_OP_SIZE + 1;
 			if (max_size && outpos > max_size)
 				break;
-			out = xrealloc(out, outsize);
+			out = realloc(out, outsize);
 			if (!out) {
 				free(tmp);
 				return NULL;