Description of problem:
* the mimedefang service file uses a wrapper which is labeled bin_t, therefore the mimedefang process ends up running as unconfined_service_t even if it should be confined

# grep Exec /usr/lib/systemd/system/mimedefang.service 
ExecStart=/usr/libexec/mimedefang-wrapper start
ExecReload=/usr/libexec/mimedefang-wrapper reload
# matchpathcon `which mimedefang`
/usr/bin/mimedefang	system_u:object_r:spamd_exec_t:s0
#

Version-Release number of selected component (if applicable):
mimedefang-2.78-6.el7.x86_64
selinux-policy-3.13.1-60.el7.noarch
selinux-policy-targeted-3.13.1-60.el7.noarch

How reproducible:
always

Steps to Reproduce:
1. get a RHEL-7.2 machine with active targeted policy
2. start the mimedefang service
3. ps -efZ | grep mimedefang
system_u:system_r:unconfined_service_t:s0 defang 32613 1  0 04:28 ?    00:00:00 /usr/bin/mimedefang-multiplexor -p /var/spool/MIMEDefang/mimedefang-multiplexor.pid -m 2 -x 10 -y 0 -U defang -b 600 -l -s /var/spool/MIMEDefang/mimedefang-multiplexor.sock
system_u:system_r:unconfined_service_t:s0 defang 32614 32613  0 04:28 ? 00:00:00 /usr/bin/perl /usr/bin/mimedefang.pl -server
system_u:system_r:unconfined_service_t:s0 defang 32629 1  0 04:28 ?    00:00:00 /usr/bin/mimedefang -P /var/spool/MIMEDefang/mimedefang.pid -m /var/spool/MIMEDefang/mimedefang-multiplexor.sock -y -R -1 -U defang -q -p /var/spool/MIMEDefang/mimedefang.sock
system_u:system_r:unconfined_service_t:s0 defang 32631 32613  1 04:28 ? 00:00:00 /usr/bin/perl /usr/bin/mimedefang.pl -server

Actual results:
# matchpathcon /usr/libexec/mimedefang-wrapper 
/usr/libexec/mimedefang-wrapper	system_u:object_r:bin_t:s0
#

Expected results:
# matchpathcon /usr/libexec/mimedefang-wrapper 
/usr/libexec/mimedefang-wrapper	system_u:object_r:spamd_exec_t:s0
#