More fixes for libfpx

[mi]

There are two patch-files in FreeBSD's port graphics/libfpx, that fix various warnings raised by newer compilers (clang-3.2, gcc-4.8). The patches are applicable to 1.3.1-2:

• Remove unused private fields from some classes
• Fix a variety of warnings and a few errors

[magick]

Thanks for the patches. Look for them in libfpx-1.3.1-3 by sometime tomorrow.