Add an exception to the LGPL for the generated libraries to allow static linking

[CLowcay]

Normally, under the terms of the LGPL, when an application is linked against an LGPL library, the end user must be able to modify and replace the LGPL part of the application. This is difficult for statically linked Haskell libraries in GHC, so application authors that use LGPL code may be obliged to supply source code for their applications.

This pull request adds an exception to the licenses of the generated bindings to explicitly allow static linking. This exception is based on https://github.com/gtkd-developers/GtkD/blob/master/COPYING.

If this exception is acceptable to the project maintainers, then I would also like to extend it to the haskell-gi-base and haskell-gi libraries since all of the generated bindings are dependent on those libraries.

[garetxe]

Thanks a lot for the pull request!

The changes to the license themselves look good, just a couple of minor comments about the code itself.

[garetxe]

Thanks a lot, merged!

I will try to find some time to re-release all bindings with the new license soon, but in the meanwhile, if there is any binding you are particularly interested in, please let me know.

[CLowcay]

Thanks for merging those license changes. Much appreciated. I will raise a second pull request very soon to apply the same license change to haskell-gi-base and haskell-gi since they are both dependencies of all the bindings.