Work around copy_file_range() bug in eCryptFs

When programs like ar.ape and compile.ape are run on eCryptFs partitions
on Linux, copy_file_range() will fail with EINVAL which is wrong because
eCryptFs which doesn't support this system call, should raise EOPNOTSUPP

See https://github.com/jart/cosmopolitan/discussions/1305

libc/thread/pthread_tryjoin_np.c

@@ -32,6 +32,7 @@
  *     if the thread called pthread_exit(), or `PTHREAD_CANCELED` if
  *     pthread_cancel() destroyed the thread instead
  * @return 0 on success, or errno on error
+ * @raise EBUSY if thread has not yet terminated
  * @raise ECANCELED if calling thread was cancelled in masked mode
  * @cancelationpoint
  * @returnserrno