Update xPortRunning before resuming first task (#1049)

The variable `xPortRunning` is now updated before starting the first
task.

It fixes the following issue -
https://forums.freertos.org/t/possible-bug-in-the-way-prvtimertask-thread-function-is-started-in-win32-port/19959/

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

portable/MSVC-MingW/port.c

@@ -353,12 +353,12 @@ BaseType_t xPortStartScheduler( void )
         pxThreadState = ( ThreadState_t * ) *( ( size_t * ) pxCurrentTCB );
         ulCriticalNesting = portNO_CRITICAL_NESTING;
 
-        /* Start the first task. */
-        ResumeThread( pxThreadState->pvThread );
-
         /* The scheduler is now running. */
         xPortRunning = pdTRUE;
 
+        /* Start the first task. */
+        ResumeThread( pxThreadState->pvThread );
+
         /* Handle all simulated interrupts - including yield requests and
          * simulated ticks. */
         prvProcessSimulatedInterrupts();