Allow apps with ACCESS_WIFI_STATE to listen for wifi networks

The compatibility measure introduced in bug 20081183 for apps
that connect to a Wi-Fi network without Internet access and then
expect to be able to use that network requires that such apps
register a NetworkCallback so that their WifiManager can pin them
to whatever wifi Network connects.

Currently, registering the callback requires ACCESS_NETWORK_STATE
and the app may not have that permission. Allow registering wifi
(only) callbacks if the app has ACCESS_WIFI_STATE.

If the app does not have ACCESS_WIFI_STATE (unlikely, since
CHANGE_WIFI_STATE is not very useful without ACCESS_WIFI_STATE),
then don't enable the compatibility measure.

Bug: 20081183
Bug: 20423580
Change-Id: Iad328d30c2d170dead883868fece3d922da68f6f