> From: Richard Copley <rcopley@gmail.com>
> Date: Mon, 21 Oct 2019 13:28:29 +0100
>
> Linking auxiliary executables fails with undefined references to (FORTIFY_SOURCE?) functions
> __memcpy_chk and __memmove_chk. This is apparently caused by some change in MSYS2, because
> previously buildable commits now fail. Transcript below.

Looks like FORTIFY_SOURCE requires linking against -lssp?  Can you try
adding that, e.g. by

  make LIBS_SYSTEM=-lssp