uru4000: Fix state change from IRQ handler

The IRQ handler will re-register itself automatically. However, if this
happens after the callback is called, then the check whether the IRQ
handler is running fails.

Re-start the IRQ handler before calling the callback. This way the state
changes happening from the callback will see the correct IRQ handler
registration state.

See: #205

libfprint/drivers/uru4000.c

@@ -332,6 +332,8 @@ irq_handler (FpiUsbTransfer *transfer,
       return;
     }
 
+  start_irq_handler (imgdev);
+
   type = GUINT16_FROM_BE (*((uint16_t *) data));
   fp_dbg ("recv irq type %04x", type);
 
@@ -344,8 +346,6 @@ irq_handler (FpiUsbTransfer *transfer,
     urudev->irq_cb (imgdev, NULL, type, urudev->irq_cb_data);
   else
     fp_dbg ("ignoring interrupt");
-
-  start_irq_handler (imgdev);
 }
 
 static void