Build jobs are failing due build error "arm_hal_timer.cpp:50:5:
error: reference to 'callback' is ambiguous".
Fix the build error by renaming callback to arm_hal_callback to
avoid collision with callback defined in ./mbed-os/hal/api/Callback.h
Move the library files used by both nanostack and client into a common
location. This allows both client and nanostack to be built stand-alone.
The patch moves the following libraries into a common location:
-mbed-client-c
-mbed-client-randlib
-mbed-trace
-nanostack-hal-mbed-cmsis-rtos
-nanostack-libservice
-sal-stack-nanostack-eventloop
And moves the library 'coap-service' from client into nanostack.