Remove quick_symbol_functions::map_symtabs_matching_filename

Remove quick_symbol_functions::map_symtabs_matching_filename

This replaces quick_symbol_functions::map_symtabs_matching_filename
with a call to expand_symtabs_matching.  As with the previous patch,
rather than update all callers, the implementation is consolidated in
objfile::map_symtabs_matching_filename.

gdb/ChangeLog
2021-04-17  Tom Tromey  <tom@tromey.com>

	* symfile-debug.c (objfile::map_symtabs_matching_filename):
	Rewrite.
	* quick-symbol.h (struct quick_symbol_functions)
	<map_symtabs_matching_filename>: Remove.
	* psymtab.c (partial_map_expand_apply)
	(psymbol_functions::map_symtabs_matching_filename): Remove.
	* psympriv.h (struct psymbol_functions)
	<map_symtabs_matching_filename>: Remove.
	* objfiles.h (struct objfile) <map_symtabs_matching_filename>:
	Update comment.
	* dwarf2/read.c (struct dwarf2_base_index_functions)
	<map_symtabs_matching_filename>: Remove.
	(dw2_map_expand_apply)
	(dwarf2_base_index_functions::map_symtabs_matching_filename):
	Remove.