Fix bug in core_cm3.c atomic macros.

Rename the portable/GCC/RISC-V-RV32 directory to just RISC-V as also adding support for 64-bit cores.

FreeRTOS/Source/portable/GCC/RISC-V/port.c

@@ -69,11 +69,6 @@ interrupt stack after the scheduler has started. */
  */
 void vPortSetupTimerInterrupt( void ) __attribute__(( weak ));
 
-/*
- * Used to catch tasks that attempt to return from their implementing function.
- */
-static void prvTaskExitError( void );
-
 /*-----------------------------------------------------------*/
 
 /* Used to program the machine timer compare register. */
@@ -108,22 +103,6 @@ task stack, not the ISR stack). */
 
 /*-----------------------------------------------------------*/
 
-static void prvTaskExitError( void )
-{
-volatile uint32_t ulx = 0;
-#warning Not currently used
-	/* A function that implements a task must not exit or attempt to return to
-	its caller as there is nothing to return to.  If a task wants to exit it
-	should instead call vTaskDelete( NULL ).
-
-	Artificially force an assert() to be triggered if configASSERT() is
-	defined, then stop here so application writers can catch the error. */
-	configASSERT( ulx == ~0UL );
-	portDISABLE_INTERRUPTS();
-	for( ;; );
-}
-/*-----------------------------------------------------------*/
-
 #if( configCLINT_BASE_ADDRESS != 0 )
 
 	void vPortSetupTimerInterrupt( void )