parse-options: fix leaks for users of OPT_FILENAME

The `OPT_FILENAME()` option will, if set, put an allocated string into
the user-provided variable. Consequently, that variable thus needs to be
free'd by the caller of `parse_options()`. Some callsites don't though
and thus leak memory. Fix those.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

apply.h

@@ -59,7 +59,7 @@ struct apply_state {
 	struct repository *repo;
 	const char *index_file;
 	enum apply_verbosity apply_verbosity;
-	const char *fake_ancestor;
+	char *fake_ancestor;
 	const char *patch_input_file;
 	int line_termination;
 	struct strbuf root;