Add support for MSVC and GitHub Actions

[sepcnt]

Get run-c and run-cu works with MSVC.

• /experimental:c11atomics and -std=c11 is required for stdatomic
• Extremely large array (>=2GB) is not allowed on Windows so we have to use a pointer instead
• CUDA also needs some work for allocation
• threads.h rather than pthreads.h for compatibility.
• time64() with QueryPerformanceCounter()

Add GitHub Actions CI for building and linting.

(This is a clean PR from #294)

[kings177]

Rust and CU version works fine, C doesn't, might be because of the experimental:c11atomics not being fully supported by MSVC?

pasting the error for better reference:

 WARNING: Failed to compile hvm.c: ToolExecError: Command "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.38.33130\\bin\\HostX64\\x64\\cl.exe" "-nologo" "-MD" "-O2" "-Brepro" "-std:c11" "/experimental:c11atomics" "-DTPC_L2=4" "-FoC:\\Users\\yanki\\hvm\\target\\release\\build\\hvm-fee5e6bdbeba46c9\\out\\2e40c9e35e9506f4-hvm.o" "-c" "src/hvm.c" with args cl.exe did not execute successfully (status code exit code: 2).
warning: hvm@2.0.12: Ignoring hvm.c and proceeding with build. The C runtime will not be available.

[sepcnt]

Rust and CU version works fine, C doesn't, might be because of the experimental:c11atomics not being fully supported by MSVC?

pasting the error for better reference:

 WARNING: Failed to compile hvm.c: ToolExecError: Command "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.38.33130\\bin\\HostX64\\x64\\cl.exe" "-nologo" "-MD" "-O2" "-Brepro" "-std:c11" "/experimental:c11atomics" "-DTPC_L2=4" "-FoC:\\Users\\yanki\\hvm\\target\\release\\build\\hvm-fee5e6bdbeba46c9\\out\\2e40c9e35e9506f4-hvm.o" "-c" "src/hvm.c" with args cl.exe did not execute successfully (status code exit code: 2).
warning: hvm@2.0.12: Ignoring hvm.c and proceeding with build. The C runtime will not be available.

Yes you will need at least msvc 17.5.
Otherwise a larger polyfill for atomic will be required.
You can check the action on the fork to view successful build configuration of all platforms.

[kings177]

could you also remove the windows disclaimer from the README.md and add that for windows, you need MSVC ver >= 17.5 please?

[kings177]

On both windows and linux seems like it's ok, can't test on a mac right now, will try it later.

[edusporto]

Tested on MacOS, all examples in examples get the same results but it seems slightly slower, could be statistically insignificant since I only ran each test once

We're still discussing a few things internally before merging, specially the changes to Net allocation
We're also still developing automated tests so it gets easier to compare such changes

[VictorTaelin]

Thanks for the PR! I really appreciate it. It changes some things I'm not aware will be safe though. I'll go through it later, when we have more tests