AArch64LoadStoreOptimizer: Correctly clear kill flags

When promoting the Load of a Store-Load pair to a COPY all kill flags
between the store and the load need to be cleared.

rdar://30402435

Differential Revision: https://reviews.llvm.org/D30110

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295512 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed