GlobalISel: support 'null' constant in translation.

It's sharing the integer G_CONSTANT for now since I don't *think* it creates
any ambiguity (even on weird archs). If that turns out wrong we can create a
G_PTRCONSTANT or something.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278423 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed