* symtab.c (multiple_symbols_ask, multiple_symbols_all)

    * symtab.c (multiple_symbols_ask, multiple_symbols_all)
        (multiple_symbols_cancel): New constants.
        (multiple_symbols_modes, multiple_symbols_mode): New static globals.
        (multiple_symbols_select_mode): New function.
        (_initialize_symtab): Add new set/show multiple-symbols commands.
        * symtab.h (multiple_symbols_ask, multiple_symbols_all)
        (multiple_symbols_cancel, multiple_symbols_select_mode): Declare.
        * ada-lang.c (user_select_syms): Add handling of new multiple-symbols
        setting.
        * linespec.c (decode_line_2): Likewise.