[SystemZ] Adjust cost functions for subtargets that use LI + LOC instead of IPM

After recent improvements which makes better use of LOC instead of IPM, the
TTI cost functions also needs to be updated to reflect this.

This involves sext, zext and xor of i1.

The tests were updated so that for z13 the new costs are expected, while the
old costs are still checked for on zEC12.

Review: Ulrich Weigand
https://reviews.llvm.org/D51339

llvm-svn: 342207