core.c (core_close): Call CLEAR_SOLIB.
(core_open): Remove comment about "should deal with shared lib".
(core_xfer_memory): If we can't xfer the usual way, try the
shared libraries.
solib.c (so_list): New fields so_bfd and so_sections{,_end}.
(find_solib): Use solib_map_sections to get ld_text.
(solib_map_sections, solib_xfer_memory): New functions.
(clear_solib): Free so_sections and close so_bfd.
tm-sunos.h: Add solib_xfer_memory, solib_add.
