Additionally improve the style of the build script.
- Instead of using platform build tools, use the CMake wrappers
- Instead of build all targets, then manually stripping, use the
CMake helpers.
Contributed by Andres Gomez.
Reviewed-by: Martin Roukala <martin.roukala@mupuf.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17184>