The situation at this stage of readfile process is now sane enough, that
the regular Pose freeing code can be called, avoiding potential
memleaks.
Note that this whole 'non-Empty object with NULL obdata' case should now
be very hypothetical, since in case a linked obdata goes missing,
Blender will generate and empty place-holder for it at read time.
Tested by artificially setting all Armature objects' obdata pointer to
null in read_data code, and loading some complex production files from
Pets Project.
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