dump_pkg_full: fix optionalfor memory leak

alpm_pkg_compute_optional returns a generated list that needs to be
free'd.

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>

src/pacman/package.c

@@ -235,6 +235,7 @@ void dump_pkg_full(alpm_pkg_t *pkg, int extra)
 	printf("\n");
 
 	FREELIST(requiredby);
+	FREELIST(optionalfor);
 	alpm_list_free(validation);
 }