Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Backports commit f2ad72b30e214d1e3e41dba36f855354dfa81832 from qemu
qobject_to_qlist() crashes on null, which is a trap for the unwary.
Return null instead.
Backports commit 2d6421a90047a83f6722832405fe09571040ea5b from qemu