[ASan/Win] Fall back to stdout if we can't print the reports to stderr

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@200804 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan/Win] Add DLL thunks for __asan_{,un}poison_memory_region

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@200809 91177308-0d34-0410-b5e6-96231b3b80d8