re PR c++/13684 (local static object variable constructed once but ctors and dtors called multiple times on same memory when called in multiple threads)

        PR c++/13684
        * cp/decl.c (expand_static_init): Use thread-safety API.
        (register_dtor_fn): Return the call, don't expand it.
        * cp/tree.c (add_stmt_to_compound): New fn.
        (stabilize_call): Use it.
        * gimplify.c (gimplify_cleanup_point_expr): Handle CLEANUP_EH_ONLY.
        (gimple_push_cleanup): Add eh_only parm.
        (gimplify_target_expr): Pass it.
        * c.opt (-fno-threadsafe-statics): New option.
        * c-opts.c (c_common_handle_option): Handle it.
        * c-common.h (flag_threadsafe_statics): Declare it.
        * c-common.c (flag_threadsafe_statics): Record it.
        * doc/invoke.texi: Document it.
        * tsystem.h (_GNU_SOURCE): Define.
        * gthr-posix.h (__gthread_recursive_mutex_t): New typedef.
        (__GTHREAD_RECURSIVE_MUTEX_INIT): New macro.
        (__GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION): New macro.
        (__gthread_recursive_mutex_init_function): New fn.
        (__gthread_recursive_mutex_lock): New fn.
        (__gthread_recursive_mutex_trylock): New fn.
        (__gthread_recursive_mutex_unlock): New fn.
        * gthr-solaris.h, gthr-single.h, gthr-dce.h: Likewise.
        * gthr-win32.h, gthr-vxworks.h: Likewise.
        * gthr.h: Document.

        * libsupc++/guard.cc (static_mutex): Internal class implementing a
        recursive mutex which controls initialization of local statics.
        (__gnu_cxx::recursive_init): New exception class.
        (__cxa_guard_acquire): Deal with locking and recursion detection.
        (acquire_1, __cxa_guard_abort, __cxa_guard_release): Likewise.

From-SVN: r86687