[LICM] Preserve DT and LoopInfo specifically

Summary:
In LICM, CFG could be changed in splitPredecessorsOfLoopExit(), which update
only DT and LoopInfo. Therefore, we should preserve only DT and LoopInfo specifically,
instead of all analyses that depend on the CFG (setPreservesCFG()).

This change should fix PR37323.

Reviewers: uabelho, davide, dberlin, Ka-Ka

Reviewed By: dberlin

Subscribers: mzolotukhin, bjope, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D46775

llvm-svn: 333198