android.hardware.common: support Java

The handle type here is needed in some HALs now (specifically in order
to encode a Surface, which is backed by a handle). This previously
wasn't in Java simply because handles are more common in native code,
and so it wasn't expected to be used.

Fixes: 171087128
Test: build
Change-Id: Ie1eaf50cc8e62932cc553b80c02be434bfbaf3b3