This patch moves further includes (the network part and lib.h) in common/.
It is the last part to get the netbsd libc to compile under minix. Further moves will be needed as we get the netbsd libc to compile minix itself.
Also, this patch add #ifndef's to termios.h, as it create problems with netbsd's namespace.h.
Headers that will be shared between old includes and NetBSD-like includes
are moved into common/include tree. They are still copied in /usr/include
in 'make includes', so compilation and programs aren't be affected.
