[bug-womb] Mpc update

[Andreas Enge]

Hello,

just a quick word to let you know that GNU MPC is in fact released under
LGPLv3+ since its 1.0 release in July 2012, as we discussed before it
became a GNU package.

Also, mpfr is released under LGPLv3+ since its 3.0.0 release in June 2010,
as can be seen from the GNU ftp server.

Finally, the same holds for GMP since version 4.2.2 in 2007.

It would be nice if you could update gnupackages.txt accordingly.

Thanks a lot,

Andreas