libgcc2.c (get_reg_addr): Don't abort if we haven't got a copy of a saved register; return NULL instead.

2001-01-17  Andrew Haley  <aph@redhat.com>

        * libgcc2.c (get_reg_addr): Don't abort if we haven't got a copy
        of a saved register; return NULL instead.
        (copy_reg): Take a pointer to a source register rather than a
        frame_state.
        (next_stack_level): Remember the address in the stack frame of all
        saved registers.
        Use the saved register pointer array as the source of the CFA.
        (throw_helper): Rewrite.  Unwind once rather than twice and keep
        track of saved registers as we go.

From-SVN: r39199