* alpha-mdebug-tdep.c (alpha_mdebug_frame_p): Reject prologues.

        (alpha_mdebug_frame_unwind_cache): Don't call the heuristic unwinder.
        (alpha_mdebug_frame_this_id): Likewise.
        (alpha_mdebug_frame_prev_register): Likewise.
        (alpha_mdebug_frame_base_address): Likewise.
        (alpha_mdebug_frame_locals_address): Likewise.
        (alpha_mdebug_frame_args_address): Likewise.
        (struct alpha_mdebug_unwind_cache): Remove in_prologue_cache.
        * alpha-tdep.c (alpha_heuristic_proc_start): Use get_pc_function_start.
        (alpha_heuristic_frame_unwind_cache): Make static; add missing
        loop increment.
        (alpha_heuristic_frame_this_id): Make static.
        (alpha_heuristic_frame_prev_register): Likewise.
        (alpha_heuristic_frame_base_address): Likewise.
        * alpha-tdep.h: Update.