This is a second attempt to fix the crash reported by Thomas[1].

This keeps the compat property array simple, different from my
first attempt[2].

This also avoids extra complexity on the device code: we don't
need interface name, inheritance tricks, or devices overriding a
compat property after the fact.  The simple absence of the QOM
properties on some device types is enough to make the compat code
skip them.

While working on the fix, I stumbled upon another minor bug in
object_apply_global_props(), which I fixed in patch 1/3.

This series is based on my machine-next branch, because of
conflicts with compat property array cleanups that are already
queued.

[1] http://mid.mail-archive.com/a28d196a-e2fe-a013-a6e2-99ac260f6279@redhat.com
[2] http://mid.mail-archive.com/20190104032226.21428-1-ehabkost@redhat.com

Eduardo Habkost (3):
  qom: Don't keep error value between object_property_parse() calls
  globals: Allow global properties to be optional
  virtio: Make disable-legacy/disable-modern compat properties optional

 include/hw/qdev-core.h | 3 +++
 hw/core/machine.c      | 5 +++--
 qom/object.c           | 6 ++++--
 3 files changed, 10 insertions(+), 4 deletions(-)

-- 
2.18.0.rc1.1.g3f1ff2140