[LICM] Allow freeze to hoist/sink out of a loop

Summary: This patch allows LICM to hoist/sink freeze instructions out of a loop.

Reviewers: reames, fhahn, efriedma

Reviewed By: reames

Subscribers: jfb, lebedev.ri, hiraditya, asbirlea, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75400