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.c

@@ -135,6 +135,7 @@ void clear_apply_state(struct apply_state *state)
 	strset_clear(&state->removed_symlinks);
 	strset_clear(&state->kept_symlinks);
 	strbuf_release(&state->root);
+	FREE_AND_NULL(state->fake_ancestor);
 
 	/* &state->fn_table is cleared at the end of apply_patch() */
 }