http.c: Drop useless != NULL test in finish_http_pack_request

The test preq->packfile != NULL is always true.  If packfile was
actually NULL when entering this function the ftell() above would
crash out with a SIGSEGV, resulting in never reaching this point.

Simplify the code by just removing the conditional.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -1005,12 +1005,9 @@ int finish_http_pack_request(struct http_pack_request *preq)
 	struct packed_git *p = preq->target;
 
 	p->pack_size = ftell(preq->packfile);
-
-	if (preq->packfile != NULL) {
 	fclose(preq->packfile);
 	preq->packfile = NULL;
 	preq->slot->local = NULL;
-	}
 
 	lst = preq->lst;
 	while (*lst != p)