[tlbuild] new clisp/libffcall/libsigsegv for testing

[Bruno Haible]

Hi Akira,

> With an attached patch: clisp-2.49.50.diff, I could build lisp.exe
> with libffcall-1.13-20170225 and libsigsegv-2.11
> by an old i686-pc-mingw32-gcc for windows:

Thank you for the patch. I'll be including it in the next prerelease.
(In fact I had already encountered a build error on mingw at this location,
but did not have time to dig deeper and fix it.)

Bruno