re PR middle-end/44566 (configuration with multiple targets / backends is not supported.)

        PR other/44566
        * coretypes.h [!USED_FOR_TARGET] (reg_class_t): Define.
        * target.def (struct gcc_target): Replace enum reg_class with
        reg_class_t in hook argument / return types.
        * doc/tm.texi.in (TARGET_SECONDARY_RELOAD): Likewise.
        (TARGET_IRA_COVER_CLASSES, TARGET_MEMORY_MOVE_COST): Likewise.
        (TARGET_BRANCH_TARGET_REGISTER_CLASS): Likewise.
        * targhooks.h (default_branch_target_register_class): Likewise.
        (default_ira_cover_classes, default_secondary_reload): Likewise.
        (default_memory_move_cost, default_register_move_cost): Likewise.
        * targhooks.c (default_branch_target_register_class): Likewise.
        (default_ira_cover_classes, default_secondary_reload): Likewise.
        (default_memory_move_cost, default_register_move_cost): Likewise.
        * reload.c (push_secondary_reload, secondary_reload_class): Likewise.
        * bt-load.c (branch_target_load_optimize): Likewise.
        * ira.c (setup_cover_and_important_classes): Likewise.
        * ira-costs.c (copy_cost): Likewise.
        * reload1.c (emit_input_reload_insns): Likewise.
        * config/alpha/alpha.c (alpha_secondary_reload): Likewise.
        * config/frv/frv.c (frv_secondary_reload): Likewise.
        * config/s390/s390.c (s390_secondary_reload): Likewise.
        * config/i386/i386.c (i386_ira_cover_classes): Likewise.
        (ix86_secondary_reload, ix86_memory_move_cost): Likewise.
        (ix86_register_move_cost): Likewise.
        * config/sh/sh-protos.h (sh_secondary_reload): Likewise.
        * config/sh/sh.c (sh_target_reg_class, sh_secondary_reload): Likewise.
        * config/xtensa/xtensa.c (xtensa_secondary_reload): Likewise.
        * config/xtensa/xtensa-protos.h (xtensa_secondary_reload): Likewise.
        * config/rs6000/rs6000.c (rs6000_secondary_reload): Likewise.
        (rs6000_ira_cover_classes): Likewise.
        * config/picochip/picochip.c (picochip_secondary_reload): Likewise.
        * config/picochip/picochip-protos.h (picochip_secondary_reload):
        Likewise.
        * config/pa/pa.c (pa_secondary_reload): Likewise.
        * config/mips/mips.c (mips_ira_cover_classes): Likewise.
        * config/bfin/bfin.c (bfin_secondary_reload): Likewise.
        * config/ia64/ia64.c (ia64_register_move_cost): Likewise.
        * doc/tm.texi: Regenerate.

From-SVN: r161633