[asan] add llvm-ish test for memset/etc instrumentation

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206747 91177308-0d34-0410-b5e6-96231b3b80d8
Reapply r206732. This time without optimization of branches.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206749 91177308-0d34-0410-b5e6-96231b3b80d8