HAVE_WORKING_FORK.
* cli/cli-cmds.c (shell_escape): Guard call to vfork with
HAVE_WORKING_VFORK and HAVE_WORKING_FORK.
* remote-fileo.c (remote_fileio_mode_to_host): Accomodate lack of
S_IRGRP and related macros.
(remote_fileio_mode_to_target): Likewise.