Generalize machine compatibility properties During "[PATCH v2 05/10] qom/globals: generalize object_property_set_globals()" review, Eduardo suggested to rework the GlobalProperty handling, so that -global is limited to QDev only and we avoid mixing the machine compats and the user-provided -global properties (instead of generalizing -global to various object kinds, like I proposed in v2). "qdev: do not mix compat props with global props" patch decouples a bit user-provided -global from machine compat properties. This allows to get rid of "user_provided" and "errp" fields in following patches. A new compat property "x-use-canonical-path-for-ramblock-id" is added to hostmem for legacy canonical path names, set to true for -file and -memfd with qemu < 4.0. (this series was initially titled "[PATCH v2 00/10] hostmem: use object "id" for memory region name with >= 3.1", but its focus is more in refactoring the global and compatilibity properties handling now)