When running these tests on non-Windows, the compiler would need to
cross-preprocess the .c sources before cross-compiling. DMD doesn't
handle that properly (on Linux, just uses the native preprocessor,
and failing badly with Apple clang on macOS). And for LDC, that would
require an installed C cross-toolchain. That'd be a ridiculous effort
for these 2 tests, so just preprocess and compile them like all other
tests, even if the original problems were on Windows only. No harm in
running these tests on Posix too while targeting Posix.
