IAR Embedded Workbench modified behaviour of weak declaration "#pragma weak" in release 8.50.5. (#83)

This modification result in build error in case of FreeRTOS CM0 port.
To fix the issue use __weak in function definition instead.

portable/IAR/ARM_CM0/port.c

@@ -96,7 +96,6 @@ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
  * file is weak to allow application writers to change the timer used to
  * generate the tick interrupt.
  */
-#pragma weak vPortSetupTimerInterrupt
 void vPortSetupTimerInterrupt( void );
 
 /*
@@ -242,7 +241,7 @@ void xPortSysTickHandler( void )
  * Setup the systick timer to generate the tick interrupts at the required
  * frequency.
  */
-void vPortSetupTimerInterrupt( void )
+__weak void vPortSetupTimerInterrupt( void )
 {
     /* Calculate the constants required to configure the tick interrupt. */
     #if ( configUSE_TICKLESS_IDLE == 1 )