Localized suppression of compiler warnings and minor fixes

[jbcoe]

• Suppress target-specific compiler warnings for non-MSVC builds

• Fix format specifier in error message

[StephenOman]

What is the purpose of limiting the noisy warning suppression to non-MVSC?

[jbcoe]

I don't think that the suppressions I have specified will work on MSVC.

We could consider

target_compile_options(makedefs PRIVATE 
    $<$<CXX_COMPILER_ID:MSVC>:/wd4996>
    $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wno-deprecated-non-prototype>
)

(or equivalent) as I think that MSVC will likely treat -Wno-deprecated-non-prototype as an unknown command-line option and trigger an error (or a warning about an invalid argument).

I don't have access to MSVC to be able to check.

[StephenOman]

I have a Windows machine here so I can see what happens with the current setup.

[StephenOman]

Pretty much what you expected:

cl : command line  error D8021: invalid numeric argument '/Wno-deprecated-non-prototype'

There are other issues too though - tmt.c (in third_party/libtmt) has variable length arrays and compiling it causes:

 error C2057: expected constant expression

These aren't supported in MVSC, so I'm not sure that NLE ever worked on Windows.

[jbcoe]

Presumably one could build a more modern C-compiler for Windows and get Nethack working?

We should avoid checking in code that we know won't work on Windows. Fixing the Windows build is probably beyond the scope of this PR.

[StephenOman]

According to the original team, NLE never worked under Windows. However, NetHack itself can be built and run.

I agree with your suggestion about not making it worse. These warning suppressions were added only because they were annoying me when I was adding new C code, so perhaps this PR should remove them completely for now to align with not adding more Windows-breaking code/configuration. They don't appear if the build is successful.

We already have an open issue with Windows Install (#34) and fixing it sounds like a bit more work.