Fix incorrect argument type in virDomainMigrate3

The 5th argument `flags` of `virDomainMigrate3` is `unsigned int`, not
`unsigned long`.  Therefore, the Java binding should use `int` instead of
`NativeLong`.

To maintain backward compatibility, the version taking `NativeLong` as an
argument has been deprecated, and a new version taking `int` has been added.

Although not fully verified, it is likely that no practical issue occurs on
supported platforms because:

- On 32-bit platforms, `long` and `int` are the same size.
- On 64-bit platforms, the 5th argument is passed via a register.

Signed-off-by: Mitsuru Kariya <mitsuru.kariya@nttdata.com>