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.
size field. The TIOCSFON ioctl size (8192) didn't get encoded properly,
as there weren't enough bits for it (12) in the regular format.
The new format has only one type field, and an extra flag (_IOC_BIG)
turned on. FS checks for this flag and uses the alternative decoding
of the ioctl codes to determine the size when doing grants.
This unbreaks loadfont, although that still uses a phys copy in tty.
