* psymtab.c (lookup_symbol_aux_psymtabs): New variable stab_best. Use
it as a fallback for TYPE_IS_OPAQUE.
* symfile.h (struct quick_symbol_functions): Mention TYPE_OPAQUE
symbols for lookup_symbol.
gdb/testsuite/
* gdb.dwarf2/dw2-icc-opaque.S: Add debug_info_seg3 and
.debug_abbrev_seg3.