Change map_matching_symbols to take a symbol_found_callback_ftype
This changes map_matching_symbols to take a
symbol_found_callback_ftype, rather than separate callback and data
parameters. This enables a future patch to clean up some existing
code so that it can more readily be shared.
gdb/ChangeLog
2019-09-10 Tom Tromey <tromey@adacore.com>