Fix SHIFT_VAR with SHORTSIZE != SIZE16

e.g. with -m32 use64bitint, SHIFT_VAR has 6 args

Author: rurban

pp_pack.c

@@ -1382,8 +1382,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, const char *s, const char *strbeg, const c
 #if SHORTSIZE != SIZE16
 	    while (len-- > 0) {
 		unsigned short aushort;
-                SHIFT_VAR(utf8, s, strend, aushort, datumtype, needs_swap,
-                          needs_swap);
+                SHIFT_VAR(utf8, s, strend, aushort, datumtype, needs_swap);
 		if (!checksum)
 		    mPUSHu(aushort);
 		else if (checksum > bits_in_uv)