dhcpcd: backport two patches to fix runtime error

dhcpcd: backport two patches to fix runtime error

In case of nodistro, dhcpcd gives us 'Bad system call'
error and exits. This is because there are syscalls that
should be allowed but not in privsep. Backport two patches
to fix this issue.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit f1e6a0c16d6685096ec9313301aa431e73d02c07)
Signed-off-by: Steve Sakoman <steve@sakoman.com>