- Switch to multibuild to avoid buildcycle

- Remove CFLAGS for noarch package
- Use setuptools to build the package
- Expand scope of fdupes to include egg-info
- Activate test suite, disabled using bcond check on platforms
without test dependency pygame, and with test_buffer_api_basic
disabled on platforms other than x86_64 and aarch64 due to
failures caused by the installation of opengel-accelerate
- Change optional dependencies tk and numpy to Recommends
instead of mandatory run time dependencies
- Add missing python-tk to Recommends to complement tk
- Change mtime adjustment algorithm to be more reflective of the
source date, based on OpenGL/__init__.py instead of .changes
- Upgrade to 3.1.3b2
- Python 3.7 compatibility fixes