knightos-scas: fix cross-compilation and enable documentation

pkgs/development/tools/knightos/scas/default.nix

···
-{ fetchFromGitHub, lib, stdenv, cmake }:
+{ fetchFromGitHub, lib, stdenv, cmake, buildPackages, asciidoc, libxslt }:
+
+let
+  isCrossCompiling = stdenv.hostPlatform != stdenv.buildPlatform;
+in
 
 stdenv.mkDerivation rec {
   pname = "scas";
···
   };
 
   cmakeFlags = [ "-DSCAS_LIBRARY=1" ];
-
+  postPatch = ''
+    substituteInPlace CMakeLists.txt \
+      --replace "TARGETS scas scdump scwrap" "TARGETS scas scdump scwrap generate_tables"
+  '';
   strictDeps = true;
 
-  nativeBuildInputs = [ cmake ];
+  depsBuildBuild = lib.optionals isCrossCompiling [ buildPackages.knightos-scas ];
+  nativeBuildInputs = [ asciidoc libxslt.bin cmake ];
+  postInstall = ''
+    cd ..
+    make DESTDIR=$out install_man
+  '';
 
   meta = with lib; {
     homepage    = "https://knightos.org/";