remove call of _fwalk

remove call of _fwalk

SCCS-vsn: usr.bin/mail/lex.c 5.21
SCCS-vsn: usr.bin/mail/names.c 5.16
SCCS-vsn: usr.bin/mail/edit.c 5.15
SCCS-vsn: usr.bin/mail/collect.c 5.22
SCCS-vsn: usr.bin/mail/cmd2.c 5.14
SCCS-vsn: usr.bin/mail/quit.c 5.15
SCCS-vsn: usr.bin/mail/send.c 5.21
SCCS-vsn: usr.bin/mail/glob.h 5.20
SCCS-vsn: usr.bin/mail/cmd3.c 5.24
SCCS-vsn: usr.bin/mail/main.c 5.27
SCCS-vsn: usr.bin/mail/fio.c 5.23
SCCS-vsn: usr.bin/mail/cmd1.c 5.21
SCCS-vsn: usr.bin/mail/popen.c 5.15
SCCS-vsn: usr.bin/mail/def.h 5.22
SCCS-vsn: usr.bin/mail/aux.c 5.20