* source.c (get_current_source_symtab_and_line)
(set_current_source_symtab_and_line): Use { 0 }.
* cli/cli-cmds.c (list_command): Likewise.
* source.c (get_current_source_symtab_and_line)
(set_current_source_symtab_and_line): Use { 0 }.
* cli/cli-cmds.c (list_command): Likewise.