Add copyright

Add copyright

SCCS-vsn: usr.bin/ex/bcopy.c 7.2
SCCS-vsn: usr.bin/ex/ex.c 7.3
SCCS-vsn: usr.bin/ex/ex_addr.c 7.2
SCCS-vsn: usr.bin/ex/ex_cmds.c 7.9
SCCS-vsn: usr.bin/ex/ex_cmds2.c 7.3
SCCS-vsn: usr.bin/ex/ex_cmdsub.c 7.6
SCCS-vsn: usr.bin/ex/ex_data.c 7.3
SCCS-vsn: usr.bin/ex/ex_extern.c 7.3
SCCS-vsn: usr.bin/ex/ex_get.c 7.5
SCCS-vsn: usr.bin/ex/ex_io.c 7.10
SCCS-vsn: usr.bin/ex/ex_put.c 7.8
SCCS-vsn: usr.bin/ex/ex_re.c 7.4
SCCS-vsn: usr.bin/ex/ex_set.c 7.3
SCCS-vsn: usr.bin/ex/ex_subr.c 7.9
SCCS-vsn: usr.bin/ex/ex_tty.c 7.9
SCCS-vsn: usr.bin/ex/ex_unix.c 7.4
SCCS-vsn: usr.bin/ex/ex_v.c 7.7
SCCS-vsn: usr.bin/ex/ex_vadj.c 7.8
SCCS-vsn: usr.bin/ex/ex_vget.c 6.7
SCCS-vsn: usr.bin/ex/ex_vmain.c 7.6
SCCS-vsn: usr.bin/ex/ex_voper.c 7.3
SCCS-vsn: usr.bin/ex/ex_vops.c 7.6