Using zig cc with CMake on Windows was failing during compiler
detection. -nostdinc was causing the crt not to be linked, and Coff/lld.zig
assumed that wWinMainCRTStartup would be present in this case.

-nostdlib did not prevent the default behaviour of linking libc++ when
zig c++ was used. This caused libc++ to be built when CMake ran
ABI detection using zig c++, which fails as libcxxabi cannot compile
under MSVC.

- Change the behaviour of COFF -nostdinc to set /entry to the function that the
default CRT method for the specified subsystem would have called.
- Fix -ENTRY being passed twice if it was specified explicitly and -nostdlib was present.
- Add support for /pdb, /version, /implib, and /subsystem as linker args (passed by CMake)
- Remove -Ddisable-zstd, no longer needed
- Add -Ddisable-libcpp for use when bootstrapping on msvc