Add Windows NT for MIPS support in clib

[lakor64]

The following PR adds Windows NT for MIPS in WATCOM C library, the compilation doesn't currently fully work due to missing CG code (which will be pushed in separate PRs)

• Added clib projects for Windows NT mips
• Added generation of export.tmp (-z flag) for RISC platforms (mps, ppc, axp)
• Implement NT MIPS startup (same as AXP for now)
• Fix heap compilation on non-8086 platform
• Add missing flags to use NT api on MIPS inside libwin32
• Add TGT_SYS check on mthread
• Stub fpu exception implementation for now (I will investigate them and make a PR to either specifiy there's no fpu exceptions or implement the relative code, or in this PR in case it's required)

[jmalak]

Thank you for your contributions.

[iainnicol]

Hi @lakor64. We are in the process of changing the Open Watcom license, from its custom license, to a more mainstream one. For a full explanation you can see the relicensing page on the Wiki.

Are you happy to licence your contributions under Apache 2.0 + LLVM Exceptions? (It's the same licence as used by LLVM and Clang.) It would be fantastic if that's okay with you.

[lakor64]

Hi @lakor64. We are in the process of changing the Open Watcom license, from its custom license, to a more mainstream one. For a full explanation you can see the relicensing page on the Wiki.

Are you happy to licence your contributions under Apache 2.0 + LLVM Exceptions? (It's the same licence as used by LLVM and Clang.) It would be fantastic if that's okay with you.

Permission granted! ✅ I would love to see Open Watcom in a better license than the current one

[iainnicol]

awesome! thank you.

[lakor64]

you can consider the commits I did and possible the future ones approved for the new license as well (I plan to send some others for mips support)