Add a "fork" of musl as //fusl.

fusl/src/process/posix_spawn_file_actions_destroy.c

+#include <spawn.h>
+#include <stdlib.h>
+#include "fdop.h"
+
+int posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *fa)
+{
+        struct fdop *op = fa->__actions, *next;
+        while (op) {
+                next = op->next;
+                free(op);
+                op = next;
+        }
+        return 0;
+}