fix warning from pack-objects.c

When compiling on ia64 I get this warning (from gcc 3.4.3):

gcc -o pack-objects.o -c -g -O2 -Wall -DSHA1_HEADER='<openssl/sha.h>'  pack-objects.c
pack-objects.c: In function `pack_revindex_ix':
pack-objects.c:94: warning: cast from pointer to integer of different size

A double cast (first to long, then to int) shuts gcc up, but is there
a better way?

[jc: Andreas Ericsson suggests to use ulong instead. ]

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 int ui = (unsigned int) p;
+	unsigned long ui = (unsigned long)(long)p;
 	int i;
 
 	ui = ui ^ (ui >> 16); /* defeat structure alignment */