Ada: allow unqualified function names in linespecs

Ada: allow unqualified function names in linespecs

This is the meat, where we replace the old la_symbol_name_compare
language method with the new ada_get_symbol_name_match_p.
It fixes the problem when trying to insert a breakpoint on "+".

gdb/ChangeLog:

        * language.h (symbol_name_match_p_ftype): New typedef.
        (struct language_defn): Replace field la_symbol_name_compare
        by la_get_symbol_name_match_p.
        * ada-lang.c (ada_get_symbol_name_match_p): New function.
        (ada_language_defn): Use it.
        * linespec.c (struct symbol_matcher_data): New type.
        (iterate_name_matcher): Rewrite.
        (iterate_over_all_matching_symtabs): Pass a pointer to
        a symbol_matcher_data struct to expand_symtabs_matching
        instead of just the lookup name.
        * c-lang.c, d-lang.c, jv-lang.c, m2-lang.c, objc-lang.c,
        opencl-lang.c, p-lang.c, language.c: Delete field
        la_symbol_name_compare, and replace by NULL for new field
        la_get_symbol_name_match_p.
        * symfile.h (struct quick_symbol_functions): Update comment.