cleanup object.h: include error.h directly

qapi/error.h is simple enough to be included in qom/object.h
direcly and prepares qom/object.h to use Error typedef.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

include/qom/object.h

@@ -18,9 +18,9 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include "qemu/queue.h"
+#include "qapi/error.h"
 
 struct Visitor;
-struct Error;
 
 struct TypeImpl;
 typedef struct TypeImpl *Type;