[X86][GlobalISel] Add limited argument lowering support to the IRTranslator.

Summary:
Add limited (i8/i16/i32/i64)  argument lowering support to the IRTranslator.
Inspired by commit 289940.

Reviewers: t.p.northover, qcolombet, ab, zvi, rovka

Reviewed By: rovka

Subscribers: dberris, rovka, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D28987

llvm-svn: 293427