Ports upstream compilation fixes and forked PKGBUILD

[aisuneko]

• Fixes upstream build error as in Adjust Python bindings for SWIG >= 4.4. sigrokproject/libsigrok#280
• Forked the PKGBUILD for https://aur.archlinux.org/packages/libsigrok-sipeed-slogic-git (I'll try to be its maintainer once the package is orphaned)

TODO

migrate from deprecated setup.py build systems.

libtool: warning: relinking 'bindings/cxx/libsigrokcxx.la'
/usr/lib/python3.14/site-packages/setuptools/_distutils/cmd.py:90: SetuptoolsDeprecationWarning: setup.py install is deprecated.
!!

        ********************************************************************************
        Please avoid running ``setup.py`` directly.
        Instead, use pypa/build, pypa/installer or other
        standards-based tools.

        This deprecation is overdue, please update your project and remove deprecated
        calls to avoid build errors in the future.

        See https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html for details.
        ********************************************************************************

!!
  self.initialize_options()
/usr/lib/python3.14/site-packages/setuptools/command/sdist.py:123: SetuptoolsDeprecationWarning: `build_py` command does not inherit from setuptools' `build_py`.
!!

        ********************************************************************************
        Custom 'build_py' does not implement 'get_data_files_without_manifest'.
        Please extend command classes from setuptools instead of distutils.

        See https://peps.python.org/pep-0632/ for details.
        ********************************************************************************

!!
  self._add_data_files(self._safe_data_files(build_py))
libtool: warning: remember to run 'libtool --finish /usr/lib'