eal/windows: fix interrupt thread ID

Interrupt thread ID retained its value after interrupt thread finish.
Other interrupt routines could then operate on the wrong thread.
Clear interrupt thread ID before thread termination.

Fixes: 5c016fc0205a ("eal/windows: add interrupt thread skeleton")
Cc: stable@dpdk.org

Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

lib/eal/windows/eal_interrupts.c

@@ -46,8 +46,11 @@ eal_intr_thread_main(LPVOID arg __rte_unused)
 			eal_intr_process(&events[i]);
 	}
 
+	intr_thread = 0;
+
 	CloseHandle(intr_iocp);
 	intr_iocp = NULL;
+
 	return NULL;
 }