[arch-dev-public] [signoff] gmp 4.2.4

[Jan de Groot]

Though gmp 4.2.3 never entered core though it was signed off, I'd like
to ask for signoff for 4.2.4, as it fixes some bugs.

At this moment only x86_64 is built, if someone can build i686 we can
signoff for that architecture also.