JIT/ppc - implement isle_i_x_x
JIT/ppc - implement isle_i_x_x

* 5 CPU ins instead of 3 (best case) for iseq/islt, but still branch-free


git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@11550 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot