[gforth] GNU libffcall 1.13 is released

[Bruno Haible]

FYI, since gforth depends on libffcall:

Available at
  https://ftp.gnu.org/gnu/libffcall/libffcall-1.13.tar.gz

New in 1.13:

* The license has been changed from GPLv2 to GPLv2+.

* Added support for the following platforms:
  (Previously, a build on these platforms failed.)
  - x86_64: Mac OS X 64-bit.
  - x86_64: Solaris 64-bit.
  - x86_64: Linux with x32 ABI: CC="gcc -mx32".
  - arm: Linux 32-bit, without hardware floats.
  - arm64: Linux 64-bit.
  - s390x: Linux 64-bit.
  - powerpc: AIX 64-bit.
  - mips: IRIX 6.5 with CC="cc -32".
  - sparc: Solaris 64-bit.

* Fixed support for the following platforms:
  (Previously, a build on these platforms appeared to succeed but was buggy.)
  - x86_64: Linux.
  - arm: Linux 32-bit, with hardware floats.
  - powerpc: Linux 64-bit.
  - mips: Linux with CC="gcc -mabi=32".
  - mips: Linux with CC="gcc -mabi=n32".
  - mips: Linux with CC="gcc -mabi=64".
  - mips: IRIX 6.5 with CC="gcc -mabi=n32".
  - s390: Linux.
  - sparc: Linux 64-bit.
  - ia64: Linux.
  - hppa: HP-UX 32-bit.

* Verified support for the following platforms:
  (A build on these platforms worked and still works.)
  - i386: Linux, Solaris, Mac OS X.
  - powerpc: Linux 32-bit.
  - powerpc: AIX 32-bit.
  - powerpc: MacOS X.
  - mips: IRIX 6.5 with CC="cc -n32".
  - sparc: Solaris 32-bit.
  - sparc: Linux 32-bit: CC="gcc -m32".
  - alpha: Linux.

* Support for a security feature: On Linux and FreeBSD platforms, linking with
  the libffcall libraries no longer causes the stack to become executable.

Bruno