[X86] Stop creating CMOV nodes with a second MVT::Glue result

Summary: We seem to inconsistently create CMOV nodes some with a Glue result and some without. But I can't find any cases that use the Glue result. So I've tried to remove all the place that did this.

Reviewers: RKSimon, spatel, zvi

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38664

llvm-svn: 315686