[asan] adding ShadowOffset64 for mips64, patch by Kumar Sukhani

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221725 91177308-0d34-0410-b5e6-96231b3b80d8
libLTO: Allow LTOCodeGenerator to own a context

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221726 91177308-0d34-0410-b5e6-96231b3b80d8