Fix QtCreator debugging on Android 5.0 devices

Add a socket based handshake method for gdb. The previous file based
method remains for now and can be activated from Qt creator. It will
be used by older creator builds but has the limitation of not working
on 5.0 devices.

The new mechanism works on pre 5.0 devices too.

Task-number: QTCREATORBUG-13418
Change-Id: Ia3ecd1b144b544f52d90940ca885653bcbc477ac
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>