Nanostack v10.1.0 for Mbed OS 5.12
* commit '780e9afb8f3b8f09e66573e7d4ba096dd9a87dd7':
Squashed 'features/nanostack/sal-stack-nanostack/' changes from 513a38e..c5ee9e4
To get Wi-Sun mesh network working, also nanostack with Wi-Sun support
is needed. ws_empty_functions.c and ws_management_api.h are temporary
included here, so that wisun_tasklet will compiled without problems.
They will replaced with the official versions with next nanostack release.