* except.c (can_throw): See through a SEQUENCE.
        (nothrow_function_p): New fn.
        * except.h: Declare it.
        * function.c (current_function_nothrow): New var.
        (prepare_function_start): Initialize it.
        * output.h: Declare it.
        * toplev.c (rest_of_compilation): Set it.
        * dwarf2out.c (dwarf2out_begin_prologue): Use it.

From-SVN: r32449