[rt-drivers] mbuff-0.7.4 and Red Hat 7.x, Kernel 2.4.x

Tomasz et al.,

Downloade mbuff 0.7.4 and re-built in under the 2.4.18-5
(vanilla) red hat kernel. As someone else discovered, 
there
is a problem because the vm_operations_struct has an entry
called unmap and it no longer exists (as you can see from
/usr/src/linux/include/linux/mm.h). Commenting out the
offending lines, makes the mbuff.o module OK. I also
replaced malloc.h with slab.h since this was recommended.

So, it builds and installs OK and passes tests 1 and 2.
I've also tried my mbuffex test suite and that appears to
work too.

Phil