except.c (convert_from_eh_region_ranges_1): Smash REG_EH_REGION notes for nothrow calls if flag_forced_unwind_exceptions.

        * except.c (convert_from_eh_region_ranges_1): Smash REG_EH_REGION
        notes for nothrow calls if flag_forced_unwind_exceptions.
        (build_post_landing_pads): Mind flag_forced_unwind_exceptions.
        (sjlj_find_directly_reachable_regions): Likewise.
        (reachable_handlers): Likewise.
        (can_throw_external): Likewise.
        (collect_one_action_chain): Record cleanups after catch-all and
        must-not-throw if flag_forced_unwind_exceptions.
        * flags.h (flag_forced_unwind_exceptions): Declare.
        * toplev.c (flag_forced_unwind_exceptions): New.
        (lang_independent_options): Add it.
	* doc/invoke.text: Add it.

        * g++.dg/eh/forced1.C: New.
        * g++.dg/eh/forced2.C: New.

From-SVN: r65158