Implements support for system level traces compatible with SEGGER
SystemView tool on top of ESP32 application tracing module.
That kind of traces can help to analyse program's behaviour.
SystemView can show timeline of tasks/ISRs execution, context switches,
statistics related to the CPUs' load distribution etc.
Also this commit adds useful feature to ESP32 application tracing module:
- Trace data buffering is implemented to handle temporary peaks of events load
When compiling in release mode, compiler was choosing same register for
oldint and intmask variables, so INTENABLE was never modified.
This effectively broke disabling of non-IRAM interrupts during flash
operations, observed in the existing tests if task watchdog is enabled.
This change adds an extra constraint tells the compiler that output
operand should not be placed into the same register as an input one.