+ enable strength reduction for -O3, probably an oversight for years that it was not included in -O3

compiler/globtype.pas

@@ -475,7 +475,7 @@ interface
        { switches being applied to all CPUs at the given level }
        genericlevel1optimizerswitches = [cs_opt_level1,cs_opt_peephole];
        genericlevel2optimizerswitches = [cs_opt_level2,cs_opt_remove_empty_proc,cs_opt_unused_para];
-       genericlevel3optimizerswitches = [cs_opt_level3,cs_opt_constant_propagate,cs_opt_nodedfa
+       genericlevel3optimizerswitches = [cs_opt_level3,cs_opt_constant_propagate,cs_opt_nodedfa,cs_opt_loopstrength
                                          {$ifndef llvm},cs_opt_use_load_modify_store{$endif},
                                          cs_opt_loopunroll,cs_opt_forloop];
        genericlevel4optimizerswitches = [cs_opt_level4,cs_opt_reorder_fields,cs_opt_dead_values,cs_opt_fastmath];