winpthreads: Update version.rc and support RC

Binutils' windres uses the C preprocessor and gets MinGW pre-defined
macros, whereas the Microsoft tool RC [1] implements its own C
preprocessor and doesn't call MSVC, so it defines a subset of the
macros.

Also update the copyright year, license field, and url of the project.

License field is updated to "MIT AND BSD-3-Clause" using SPDX [2]
identifiers and expressions, removing ZPL, considering the COPYING
file in winpthreads.

[1]: https://learn.microsoft.com/en-us/windows/win32/menurc/resource-compiler
[2]: https://spdx.dev/use/specifications/

Signed-off-by: Antonin Décimo <antonin@tarides.com>
Signed-off-by: Martin Storsjö <martin@martin.st>