xSemaphoreGetMutexHolder( SemaphoreHandle_t xMutex );
Return the handle of the task that holds the mutex specified by the function parameter, if any.
xSemaphoreGetMutexHolder() can be used reliably to determine if the calling task
is the mutex holder, but cannot be used reliably if the mutex is held by any task
other than the calling task. This is because the mutex holder might change
between the calling task calling the function, and the calling task testing the
functionís return value.
configUSE_MUTEXES must be set to 1 in FreeRTOSConfig.h for xSemaphoreGetMutexHolder() to be available.