[LoopSimplifyCFG] Use DTU.applyUpdates instead of insert/deleteEdge

`insert/deleteEdge` methods in DTU can make updates incorrectly in some cases
(see https://bugs.llvm.org/show_bug.cgi?id=40528), and it is recommended to
use `applyUpdates` methods instead when it is needed to make a mass update in CFG.

Differential Revision: https://reviews.llvm.org/D57316
Reviewed By: kuhar


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353502 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed