Label /sbin/iw as ifconfig_exec_t

iw manpage says "iw - show / manipulate wireless devices and their
configuration".  Label this command ifconfig_exec_t to allow it to
manage wireless communication devices.

Debian installs iw in /sbin/iw, Fedora in /usr/sbin/iw and Arch Linux in
/usr/bin/iw (with /usr/sbin being a symlink to /usr/bin).
Allow iw to create generic netlink sockets

iw uses generic netlink socket to configure WiFi properties.  For
example, "strace iw dev wlan0 set power_save on" outputs:

    socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC) = 3
    setsockopt(3, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
    setsockopt(3, SOL_SOCKET, SO_RCVBUF, [32768], 4) = 0
    bind(3, {sa_family=AF_NETLINK, pid=7836, groups=00000000}, 12) = 0

Some AVC denials are reported in audit.log:

    type=AVC msg=audit(1408829044.820:486): avc:  denied  { create } for
    pid=5950 comm="iw" scontext=system_u:system_r:ifconfig_t
    tcontext=system_u:system_r:ifconfig_t tclass=netlink_socket
    permissive=1
    type=AVC msg=audit(1408829044.820:487): avc:  denied  { setopt } for
    pid=5950 comm="iw" scontext=system_u:system_r:ifconfig_t
    tcontext=system_u:system_r:ifconfig_t tclass=netlink_socket
    permissive=1
    type=AVC msg=audit(1408829044.820:488): avc:  denied  { bind } for
    pid=5950 comm="iw" scontext=system_u:system_r:ifconfig_t
    tcontext=system_u:system_r:ifconfig_t tclass=netlink_socket
    permissive=1
    type=AVC msg=audit(1408829044.820:489): avc:  denied  { getattr }
    for  pid=5950 comm="iw" scontext=system_u:system_r:ifconfig_t
    tcontext=system_u:system_r:ifconfig_t tclass=netlink_socket
    permissive=1
    type=AVC msg=audit(1408829044.820:490): avc:  denied  { write } for
    pid=5950 comm="iw" scontext=system_u:system_r:ifconfig_t
    tcontext=system_u:system_r:ifconfig_t tclass=netlink_socket
    permissive=1

Allowing ifconfig_t to create generic netlink sockets fixes this.

(On a side note, the AVC denials were caused by TLP, a tool which
applies "laptop configuration" when switching between AC and battery
with the help of a udev script)
Use create_netlink_socket_perms when allowing netlink socket creation

create_netlink_socket_perms is defined as:

    { create_socket_perms nlmsg_read nlmsg_write }

This means that it is redundant to allow create_socket_perms and
nlmsg_read/nlmsg_write.

Clean up things without allowing anything new.
Add comment for iw generic netlink socket usage
Module version bump for /sbin/iw support from Nicolas Iooss.