When storing an opaque pointer value in a uint, the
appropriate type is uintptr_t which is guaranteed to
be wide enough to hold a pointer.
This is particularly important when the code can be
compiled in a sim or unit test environment which is
intended to run on a 64-bit machine.
Conflicts:
flight/targets/DiscoveryF4/System/pios_board.c
flight/targets/FlyingF4/System/pios_board.c
flight/targets/Freedom/System/pios_board.c
flight/targets/Quanton/System/pios_board.c
