functions in all projects to work properly.

mbed HAL API and NRF52 prototype implementation. Stdout can be
send to SWO using platform.swo-enable and serial can be disabled
using platform.stdio-enable.

- move swo init to SystemInit (in system_nrf52.c)
- add swo init code that resumes tracing after device reset
- change swo enable to use already existing macro name

The serial serial_free() tried to compare address of a member
of a struct, instead of the struct itself. This gives a warning
on GCC&ARMCC, but a error on IAR.

The fix here is not beautiful, a proper one would likely
avoid the memcpy() on serial_init() and have a proper way of
identifying the stdio-uart.

---8<---8<---8<---
Compile [100.0%]: serial_api.c
[Error] serial_api.c@382,0: [Pe042]: operand types are
incompatible ("serial_t *" and "struct serial_s *")
[ERROR]
          if(&stdio_uart == &(obj->serial))

The nanostack hal's critical section uses a mutex for mutual exclusion,
which is nice for many use cases. But when one needs to use the critical
section from interrupts, the RTX will have a assertion failure and panic.

Add a configurable for mbed_lib, which can be used to enable a alternative
version of critical section, which uses the underlying OS primitives, which
disables the interrupts.

Note: the default behavior is not changed, one needs to override the
"nanostack-hal.critical-section-usable-from-interrupt" to have "true".

Reason for this change is that there is a need for sending events using
nanostack event queue from interrupt context, eg. from a socket callback.

The nanostack hal's critical section uses a mutex for mutual exclusion,
which is nice for many use cases. But when one needs to use the critical
section from interrupts, the RTX will have a assertion failure and panic.

Add a configurable for mbed_lib, which can be used to enable a alternative
version of critical section, which uses the underlying OS primitives, which
disables the interrupts.

Note: the default behavior is not changed, one needs to override the
"nanostack-hal.critical-section-usable-from-interrupt" to have "true".

Reason for this change is that there is a need for sending events using
nanostack event queue from interrupt context, eg. from a socket callback.

The separate eventloop thread may not be necessary on all uses, as one
can use the existing main thread for event dispatching. Add a
conditional nanostack-hal.event-loop-dispatch-from-application, which
disables the thread creation.

Note: the ns_hal_init must be ran from the same thread which will be
used to execute the event loop later.

…read

The thread flag signaling mechanism is problematic if a separate event
loop thread is not used. The problem is, that one needs to know the
thread id of the loop dispathcer, and that knowledge can be derived
only from the caller thread of the initialization function.

Remove the magic connection from caller thread to dispatcher thread
by using event flags instead of thread flags on signaling. As the
event flags require the massive amount 20 bytes of RAM whereas
thread flags requires none, keep the code behind flag.

…fix-diverge

Fix problem with mbedtls selftest

Fix legacy size from NRF51.