Based on https://reviews.llvm.org/D42519, this ports the sanitizer version of scudo to Windows.
Passes lit tests and when used as the allocator for LLVM, that passes check-all. Have noticed that on LLVM with Scudo, https://bugs.llvm.org/show_bug.cgi?id=24978 does intermittently occur when running lli tests.
For more details of evaluation see https://reviews.llvm.org/D86694
A separate review will allow hooking this in as the memory allocator for LLVM.
I'm aware that scudo sanitizer version is not under active development. This is intended as a step to porting scudo standalone.