Merge in data regarding *docnames* from a different domaindata inventory
        (coming froma subprocess in a parallel build).

def merge_domaindata(self, docnames, otherdata):
        """Merge in data regarding *docnames* from a different domaindata inventory
        (coming froma subprocess in a parallel build).
        """
        for fullname, (fn, objtype) in otherdata['objects'].items():
            if fn in docnames:
                self.data['objects'][fullname] = (fn, objtype)
        for modname, data in otherdata['modules'].items():
            if data[0] in docnames:
                self.data['modules'][modname] = data
        for labelname, data in otherdata['labels'].items():
            if data[0] in docnames:
                self.data['labels'][labelname] = data
        for anonlabelname, data in otherdata['anonlabels'].items():
            if data[0] in docnames:
                self.data['anonlabels'][anonlabelname] = data