Add QtAndroidExtras to dependency list of QtConnectivity

We only need it for Android builds though.

Change-Id: I760dfd6038da2d4061326dd361ac517c9e674239
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>