x32. Fixes a bug in i8mem_NOREX declaration.

The old implementation assumed LP64 which is broken for x32.  Specifically, the
MOVE8rm_NOREX and MOVE8mr_NOREX, when selected, would cause a 'Cannot emit
physreg copy instruction' error message to be reported.

This patch also enable the h-register*ll tests for x32.

Differential Revision: http://reviews.llvm.org/D12336

Patch by João Porto

llvm-svn: 247058