Fixing tap adapter for win32

This fix allows connection of internal VLAN to the external TAP interface.
If tap_win32_write function always returns 0, the TAP network interface
in QEMU is disabled.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

net/tap-win32.c

@@ -480,7 +480,7 @@ static int tap_win32_write(tap_win32_overlapped_t *overlapped,
         }
     }
 
-    return 0;
+    return write_size;
 }
 
 static DWORD WINAPI tap_win32_thread_entry(LPVOID param)