esp32: SEGGER SystemView Tracing Support

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

components/freertos/port.c

@@ -105,6 +105,8 @@
 
 #include "esp_crosscore_int.h"
 
+#include "esp_intr_alloc.h"
+
 /* Defined in portasm.h */
 extern void _frxt_tick_timer_init(void);
 
@@ -112,6 +114,13 @@ extern void _frxt_tick_timer_init(void);
 extern void _xt_coproc_init(void);
 
 
+#if CONFIG_FREERTOS_CORETIMER_0
+    #define SYSTICK_INTR_ID (ETS_INTERNAL_TIMER0_INTR_SOURCE+ETS_INTERNAL_INTR_SOURCE_OFF)
+#endif
+#if CONFIG_FREERTOS_CORETIMER_1
+    #define SYSTICK_INTR_ID (ETS_INTERNAL_TIMER1_INTR_SOURCE+ETS_INTERNAL_INTR_SOURCE_OFF)
+#endif
+
 /*-----------------------------------------------------------*/
 
 unsigned port_xSchedulerRunning[portNUM_PROCESSORS] = {0}; // Duplicate of inaccessible xSchedulerRunning; needed at startup to avoid counting nesting
@@ -122,7 +131,7 @@ unsigned port_interruptNesting[portNUM_PROCESSORS] = {0};  // Interrupt nesting
 // User exception dispatcher when exiting
 void _xt_user_exit(void);
 
-/* 
+/*
  * Stack initialization
  */
 #if portUSING_MPU_WRAPPERS
@@ -222,12 +231,14 @@ BaseType_t xPortSysTickHandler( void )
 	BaseType_t ret;
 
 	portbenchmarkIntLatency();
+	traceISR_ENTER(SYSTICK_INTR_ID);
 	ret = xTaskIncrementTick();
 	if( ret != pdFALSE )
 	{
 		portYIELD_FROM_ISR();
+	} else {
+		traceISR_EXIT();
 	}
-
 	return ret;
 }