sljit and bpfjit support commited to the tree

Hi,

I committed sljit and bpfjit support to all 10 powerpc arches. It's not
enabled by default, you need to set MKSLJIT explicitly and enable SLJIT
and BPFJIT options in kernel configs. Kernel modules aren't built for
evbppc but they can be easily added later.

I don't have any powerpc hardware nor a simulator to test my changes
and I'd like to ask for a help.

Once you have a system with these options enabled, it's very easy to
test basic functionality:

 - Run tcpdump with some filter and check for "jit" entries in fstat
   output. If you see them and tcpdump produces a reasonable output,
   it's all good.
 - You can run sljit iand bpfjit tests. They are in
   /usr/tests/lib/libbpfjit/ and /usr/tests/lib/libsljit/ directories.

Thanks,
Alex