Fix: avoid set but unused variable warning in pxPortInitialiseStack (#1320)

Author: razrbro

portable/ThirdParty/GCC/Posix/port.c

@@ -229,6 +229,7 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
  /* Ensure that there is enough space to store Thread_t on the stack. */
  ulStackSize = ( size_t ) ( pxTopOfStack + 1 - pxEndOfStack ) * sizeof( *pxTopOfStack );
  configASSERT( ulStackSize > sizeof( Thread_t ) );
+ ( void ) ulStackSize; /* suppress set but not used warning */
 
  thread->pxCode = pxCode;
  thread->pvParams = pvParameters;