* symfile.c (build_section_addr_info_from_bfd): New.
(build_section_addr_info_from_objfile): Base it on
build_section_addr_info_from_bfd.
(addrs_section_compar, addrs_section_sort): New.
(addr_info_make_relative): New variables my_cleanup, abfd_addrs,
addrs_sorted, abfd_addrs_sorted and addrs_to_abfd_addrs. Build
addrs_to_abfd_addrs. Use it for recalculating ADDRS.
gdb/testsuite/
* gdb.base/dup-sect.exp, gdb.base/dup-sect.S: New.
