build: move QAPI definitions for QEMU out of qapi-obj-y

build: move QAPI definitions for QEMU out of qapi-obj-y

There is no reason why for example qemu-ga should include all the
definitions for the QEMU monitor.  However, there are a few
that are needed (qapi_free_SocketAddress, qapi_free_InetSocketAddress,
ErrorClass_lookup).  These should be moved to a separate "core"
.json schema that goes into libqemuutil.a.

For now, make this clearer by moving the qapi-*.o definitions out
of libqemuutil.a.  Once the above refactoring is done, qga-obj-y
should not include anymore qapi-types.o and qapi-visit.o.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>