[compiler-rt][windows] Test fixups for MSVC. (#109887)
- add XFAIL/UNSUPPORTED annotations for tests run wtih real MSVC
- macroify usages of clang-specific attributes in asan tests
- Add substitution for /Oy-/-fno-omit-frame-pointer
This makes the dll_intercept_memset test work with mingw
These are most of the changes that are required to get things running
with MSVC, however there are some remaining build-flag tweaks.
Nothing in here should be a functional change.
