* solib.c (solib_break_names): Define for Solaris and Linux.

    * solib.c (solib_break_names): Define for Solaris and Linux.
        (enable_break): For SVR4 systems, first try to use the debugger
        interfaces in the dynamic linker to track shared library events
        as they happen, then fall back to BKPT_AT_SYMBOL code.  Convert
        BKPT_AT_SYMBOL code to use shared library event breakpoints.
        (solib_create_inferior_hook): Simplify BKPT_AT_SYMBOL code,
        it no longer needs to restart/wait on the inferior.
        * symfile.c (find_lowest_section): No longer static.
        * symfile.h (find_lowest_section): Corresponding changes.
Wraps up 7763 work, simplifies BKPT_AT_SYMBOL code somewhat, and allows
debugging of startup code.