gdb/

gdb/
	Code cleanup.
	* breakpoint.c (print_breakpoint_location): Replace bp_location field
	source_file references by symtab field references.  Remove variables
	sal and fullname.
	(momentary_breakpoint_from_master, add_location_to_breakpoint):
	(clear_command, say_where): Replace bp_location field source_file
	references by symtab field references.
	(bp_location_dtor): Remove the source_file reference.
	(update_static_tracepoint): Replace bp_location field source_file
	references by symtab field references.
	(breakpoint_free_objfile): New function.
	* breakpoint.h (struct bp_location): Extend the comment for line_number.
	Replace the field source_file by field symtab, extend its comment.
	(breakpoint_free_objfile): New declaration.
	* objfiles.c (free_objfile): Call breakpoint_free_objfile.
	* tui/tui-winsource.c (tui_update_breakpoint_info): Replace bp_location
	field source_file references by symtab field references.