Chain dependencies used to enforce memory order should have latency of 0 (except...

Chain dependencies used to enforce memory order should have latency of 0 (except for true dependency of Store followed by aliased Load... we estimate that case with a single cycle of latency assuming the hardware will bypass)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85807 91177308-0d34-0410-b5e6-96231b3b80d8