* df-scan.c (df_scan_free_ref_vec, df_scan_free_mws_vec): New
macros.
(df_scan_free_internal): Free data structures not
allocated in storage pools.
(df_mw_hardreg_chain_delete_eq_uses): Use df_scan_free_mws_vec.
(df_refs_add_to_chains): Use df_scan_free_ref_vec and
df_scan_free_mws_vec.
* dse.c (dse_step6): Free offset_map_p and offset_map_n
unconditionally.