Re-fix compilation warnings.

Commit 8fcf1ad9c6 has a
combination of double cast and Andreas' switch to using
unsigned long ... just the latter is sufficient (and a lot less
ugly than using the double cast).

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

pack-objects.c

@@ -99,7 +99,7 @@ static int reused_delta = 0;
 
 static int pack_revindex_ix(struct packed_git *p)
 {
-	unsigned long ui = (unsigned long)(long)p;
+	unsigned long ui = (unsigned long)p;
 	int i;
 
 	ui = ui ^ (ui >> 16); /* defeat structure alignment */