Add configCLEAR_TICK_INTERRUPT() to the IAR and RVDS Cortex-A9 ports.

Replace LDMFD with POP instructions in IAR and RVDS Cortex-A9 ports.
Replace branch to address with indirect branch and exchange to address in register in the IAR and RVDS Cortex-A9 ports.

FreeRTOS/Source/tasks.c

@@ -1678,7 +1678,9 @@ UBaseType_t uxSavedInterruptStatus;
 	portASSERT_IF_INTERRUPT_PRIORITY_INVALID();
 
 	uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
-	xReturn = xTickCount;
+	{
+		xReturn = xTickCount;
+	}
 	portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );
 
 	return xReturn;