lc3tools: move env variable(s) into env for structuredAttrs

pkgs/by-name/lc/lc3tools/package.nix

@@ -41,10 +41,12 @@ stdenv.mkDerivation {
     readline
   ];
 
-  # lumetta published this a while ago but handrolled his configure
-  # jank in the original packaging makes this necessary:
-  LIBS = "${flex}/lib:${ncurses}/lib:${readline}/lib";
-  INCLUDES = "${flex}/include:${ncurses}/include:${readline}/include";
+  env = {
+    # lumetta published this a while ago but handrolled his configure
+    # jank in the original packaging makes this necessary:
+    LIBS = "${flex}/lib:${ncurses}/lib:${readline}/lib";
+    INCLUDES = "${flex}/include:${ncurses}/include:${readline}/include";
+  };
 
   # it doesn't take `--prefix`
   prefixKey = "--installdir ";