Make git pack files use little-endian size encoding

This makes it match the new delta encoding, and admittedly makes the
code easier to follow.

This also updates the PACK file version to 2, since this (and the delta
encoding change in the previous commit) are incompatible with the old
format.

pack-objects.c

@@ -51,32 +51,19 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
  */
 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 {
-	int n = 1, i;
+	int n = 1;
 	unsigned char c;
 
 	if (type < OBJ_COMMIT || type > OBJ_DELTA)
 		die("bad type %d", type);
 
-	/*
-	 * Shift the size up by 7 bits at a time,
-	 * until you get bits in the "high four".
-	 * That will be our beginning. We'll have
-	 * four size bits in 28..31, then groups
-	 * of seven in 21..27, 14..20, 7..13 and
-	 * finally 0..6.
-	 */
-	if (size) {
-		n = 5;
-		while (!(size & 0xfe000000)) {
-			size <<= 7;
-			n--;
-		}
-	}
-	c = (type << 4) | (size >> 28);
-	for (i = 1; i < n; i++) {
+	c = (type << 4) | (size & 15);
+	size >>= 4;
+	while (size) {
 		*hdr++ = c | 0x80;
-		c = (size >> 21) & 0x7f;
-		size <<= 7;
+		c = size & 0x7f;
+		size >>= 7;
+		n++;
 	}
 	*hdr = c;
 	return n;
@@ -148,7 +135,7 @@ static void write_pack_file(void)
 	else
 		f = sha1create("%s.%s", base_name, "pack");
 	hdr.hdr_signature = htonl(PACK_SIGNATURE);
-	hdr.hdr_version = htonl(1);
+	hdr.hdr_version = htonl(PACK_VERSION);
 	hdr.hdr_entries = htonl(nr_objects);
 	sha1write(f, &hdr, sizeof(hdr));
 	offset = sizeof(hdr);