python.pkgs.pyglet: hardcode library paths

[timokau]

Motivation for this change

The new way to find libraries (basically a switch statement) isn't particularly pretty, but its simple and reliable. The old way failed to load libc, since libc.so is actually a linker script so we need to directly provide the path to libc.so.6. Other libraries were missing completely.

I tried to run the Cartpole example of rl-coach, which failed to render anything before and runs perfectly now.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

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[timokau]

@GrahamcOfBorg build python2.pkgs.pyglet python3.pkgs.pyglet