freetalk: pull pending fix for -fno-common toolchains

Without the change build on -fno-common toolchains like clamng-13 fails as:

    $ nix build --impure --expr 'with import ./. {}; freetalk.override { stdenv = clang13Stdenv; }' -L
    ...
    ld: more.o:src/./more.h:15: multiple definition of `cin'; primitives.o:src/./more.h:15: first defined here
    ld: more.o:src/./more.h:14: multiple definition of `initial_settings'; primitives.o:src/./more.h:14: first defined here

pkgs/applications/networking/instant-messengers/freetalk/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub
+{ lib, stdenv, fetchFromGitHub, fetchpatch
 , guile, pkg-config, glib, loudmouth, gmp, libidn, readline, libtool
 , libunwind, ncurses, curl, jansson, texinfo
 , automake, autoconf }:
@@ -13,6 +13,16 @@ stdenv.mkDerivation rec {
     sha256 = "09jwk2i8qd8c7wrn9xbqcwm32720dwxis22kf3jpbg8mn6w6i757";
   };
 
+  patches = [
+    # Pull pending patch for -fno-common tuulchain support:
+    #   https://github.com/GNUFreetalk/freetalk/pull/39
+    (fetchpatch {
+      name = "fno-common.patch";
+      url = "https://github.com/GNUFreetalk/freetalk/commit/f04d6bc8422be44cdf51b29c9a4310f20a18775a.patch";
+      sha256 = "1zjm56cdibnqabgcwl2bx79dj6dmqjf40zghqwwb0lfi60v1njqf";
+    })
+  ];
+
   preConfigure = ''
     ./autogen.sh
   '';