Change map_matching_symbols to take a symbol_found_callback_ftype

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>

	* ada-lang.c (aux_add_nonlocal_symbols): Change type.
	(add_nonlocal_symbols): Update.
	* dwarf2read.c (dw2_map_matching_symbols): Change type.
	* psymtab.c (map_block, psym_map_matching_symbols): Change type.
	* symfile-debug.c (debug_qf_map_matching_symbols): Change type.
	* symfile.h (struct quick_symbol_functions) <map_matching_symbols>:
	Change type of "callback".  Remove "data".