Mark some files FD_CLOEXEC to protect sendmail from them.

Mark some files FD_CLOEXEC to protect sendmail from them.

From: Doug Ledford <dledford@redhat.com>

When running with SELinux enabled and using mdadm to monitor devices,
attempts to send emails to an admin will be blocked because mdadm is
holding open /proc/mdstat without setting the FD_CLOEXEC flag.  As a
result, sendmail has an open descriptor to /proc/mdstat after the
popen() call, which SELinux decides isn't really any of sendmail's
business and so sendmail gets denied.