[DAG, X86] Fix ISel-time node insertion ids

As in SystemZ backend, correctly propagate node ids when inserting new
unselected nodes into the DAG during instruction Seleciton for X86
target.

Fixes PR36865.

Reviewers: jyknight, craig.topper

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D44797

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328233 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed