RETURN => return, remove syscontext.h

RETURN => return, remove syscontext.h

SCCS-vsn: sys/kern/kern_acct.c 7.12
SCCS-vsn: sys/kern/kern_clock.c 7.9
SCCS-vsn: sys/kern/kern_descrip.c 7.15
SCCS-vsn: sys/kern/kern_exec.c 7.28
SCCS-vsn: sys/kern/kern_exit.c 7.25
SCCS-vsn: sys/kern/kern_fork.c 7.18
SCCS-vsn: sys/tahoe/tahoe/machdep.c 7.13
SCCS-vsn: sys/kern/kern_ktrace.c 7.8
SCCS-vsn: sys/tahoe/tahoe/sys_machdep.c 7.5
SCCS-vsn: sys/kern/kern_prot.c 7.12
SCCS-vsn: sys/kern/kern_resource.c 7.9
SCCS-vsn: sys/kern/kern_sig.c 7.22
SCCS-vsn: sys/kern/kern_time.c 7.12
SCCS-vsn: sys/kern/kern_xxx.c 7.13
SCCS-vsn: sys/kern/sys_generic.c 7.21
SCCS-vsn: sys/kern/sys_process.c 7.12
SCCS-vsn: sys/kern/sysv_shm.c 7.9
SCCS-vsn: sys/kern/uipc_syscalls.c 7.18
SCCS-vsn: sys/vax/vax/machdep.c 7.30
SCCS-vsn: sys/kern/vfs_syscalls.c 7.55
SCCS-vsn: sys/vax/vax/sys_machdep.c 7.5
SCCS-vsn: sys/vm/vm_swap.c 7.13