ALLJOYN-2314: Fix OpenWrt build issue for services

Properly handle the 'cpp' binding so that services will be built within the
OpenWrt build framework.

Change-Id: Ide05578f272f04a2b4851bb3ffca94a9fafe78d7
ALLJOYN-2312 Implement a new Daemon Transport to support AllJoyn thin clients
connecting to the daemon over UART using the Serial Line AllJoyn Protocol(SLAP) protocol.