RNA: existing type check used wrong identifier

Own error in recent type checks, in many cases the 'idname'
is used for the struct identifier, not the 'identifier'
which is the Python class name in this context.

source/blender/makesrna/intern/rna_render.c

@@ -321,7 +321,7 @@ static StructRNA *rna_RenderEngine_register(Main *bmain, ReportList *reports, vo
 			break;
 		}
 	}
-	if (!RNA_struct_available_or_report(reports, identifier)) {
+	if (!RNA_struct_available_or_report(reports, dummyet.idname)) {
 		return NULL;
 	}