Delete search_symbols_equal (use compare_search_syms instead).

Delete search_symbols_equal (use compare_search_syms instead).

This avoids duplicating the logic comparing two symbol_search
objects (in search_symbols_equal and compare_search_syms).

gdb/ChangeLog:

        * symtab.c (search_symbols_equal): Delete.
        (sort_search_symbols_remove_dups): Replace call to
        search_symbols_equal by call to compare_search_syms,
        adjusting as necessary.