[test] Define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST in msvc_stdlib_force_include.hpp

...so the tests under test/std/utilities/any continue to
compile with MSVC's standard library.

While we're here, let's test >C++17 features when _HAS_CXX20.

llvm-svn: 351991
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Cr-Mirrored-Commit: 1ecf6e55cd8b2ebeb506f5c5ce8080a616b4ac5b
1 file changed