o Ureg.pc -> Ureg.ip:
	- sys/src/nix/k10/acore.c
	- sys/src/nix/k10/fpu.c
	- sys/src/nix/k10/syscall.c
	- sys/src/nix/k10/trap.c;

	
o Macro constant SEGMAXPG replaced by SEGMAXSIZE, aligned with 9k
	even if, for now, it is defined equal to SEGMAPSIZE:
	- sys/src/nix/port/portdat.h

o NSEC (9k) syscall added to Nix, and added Nix syscalls defined
	as supplementary (after) to keep compatibility with current userland:
	- sys/src/libc/9syscall/mkfile
 	- sys/src/libc/9syscall/sys.h
 	- sys/src/nix/k10/syscall.c
	- sys/src/nix/mk/parse
	- sys/src/nix/port/syscallfmt.c
	- sys/src/nix/port/sysproc.c;
	
o port/tod.c is updated from 9k, with todget() taking a
	supplementary parameter and providing monotonic time;

o port/portdat.h:Ar0 union: addition of vlong (.vl).
