[En-Nut-Discussion] unix emulation on red had enterprise linux

[Matthias Ringwald]

hi

red had enterprise linux redefines the errno global, so compilation of 
the unix emulation fails there.

I fixed this in the errno.h of nut by redirecting the precompiler to 
the native errno.h file using errno_orig.h.

Make sure to run ./configure again to create an include/errno_orig.h 
after updating cvs

matthias