[GlobalIsel][X86] Support G_PTRTOINT instruction.

Add legalization/selection for x86/x86_64 and
corresponding tests.

Reviewed By: igorb

Differential Revision: https://reviews.llvm.org/D43617



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326311 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed