Create qemu-types.h for struct typedefs

Create qemu-types.h for struct typedefs

Instead of keeping all those struct typedefs in qemu-common.h, move it
to a header that can be safely included by other headers, containing
only the struct typedefs and not pulling in other dependencies.

Also, move some of the qdev-core.h typedefs to the new file, too, so
other headers don't need to include qdev-core.h only because of
DeviceState and other typedefs.

This will help us remove qemu-common.h dependencies from some headers
later.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>