[CGP] Fix the handling select inst in complex addressing mode

When we put the value in select placeholder we must pass
the value through simplification tracker due to the value might
be already simplified and erased.

This is a fix for PR35658.

Reviewers: john.brawn, uabelho
Reviewed By: john.brawn
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D41251

llvm-svn: 320956