[pf4freebsd] Version 0.63 released

[Max Laier]

Hello,

once started on the cksum-bottleneck Pyun did some further improvements to
in4_cksum, which now uses optimized code for i386 architectures. If you have
another architecture please take a look at the changes made (it's mostly
copy'n'paste from machine/in_cksum.{h, c}) and try to build a similar
approach for your architecture. Any imput is greatly appreachiated.
Furthermore Pyun has identified a problem when building on latest -current
(limits.h moved) and fixed it.

Thanks
    Max