nixos moment

on NixOS, awtfdb does not work out of the box because library paths are hard-coded.

currently I can use autoPatchelfHook to fix this just fine, but the hope is that eventually i can build awtfdb locally and entirely circumvent this issue.

to facilitate this: it would be great to have some way to either

• specify the library paths manually, or
• automatically search for the libraries if they don't exist at the default path, akin to pkg-config or similar

i have no idea how feasible the second option is, so the easiest would probably just be the first - i.e. check if some file specifying library paths exists, and then use those over the default paths.