version 2.4.0 tagged and uploaded

FYI, I have tagged and uploaded the final 2.4.0 release.  There is now a
'gnutls_2_4_x' branch.  Windows and debian mingw32 packages are also
available, and I will test them on a separate machine.  You can help by
testing the packages early too, but the only possibility to fix things
at this point is to roll a 2.4.1 and announce that instead of 2.4.0.

ftp://ftp.gnu.org/gnu/gnutls/

/Simon