gforth: override swig, not swig3

This removes one of two remaining usages of the top-level `swig3` expression.
(The other comes from older LLDB versions.)

Also removes use of overrideDerivation in favour of preferred overrideAttrs.

pkgs/development/compilers/gforth/swig.nix

@@ -1,8 +1,12 @@
-{ swig3, fetchFromGitHub }:
+{
+  swig,
+  pcre,
+  fetchFromGitHub,
+}:
 
 ## for updating to swig4, see
 ## https://github.com/GeraldWodni/swig/pull/6
-swig3.overrideDerivation (old: {
+(swig.overrideAttrs (old: {
   version = "3.0.9-forth";
   src = fetchFromGitHub {
     owner = "GeraldWodni";
@@ -10,7 +14,6 @@ swig3.overrideDerivation (old: {
     rev = "a45b807e5f9d8ca1a43649c8265d2741a393862a";
     sha256 = "sha256-6nOOPFGFNaQInEkul0ZAh+ks9n3wqCQ6/tbduvG/To0=";
   };
-  configureFlags = old.configureFlags ++ [
-    "--enable-forth"
-  ];
-})
+  configureFlags = old.configureFlags ++ [ "--enable-forth" ];
+})).override
+  { pcre2 = pcre; }