knightos: reduce build time dependency graph

Using asciidoc-full was unnecessary to build KnightOS-related packages
since only the a2x command matters. This change makes
cross-compilation far more noticeably faster. Closure size for each
package reduced from around 7 MB to 2 MB.

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

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, cmake, asciidoc, libxslt, docbook_xsl }:
+{ lib, stdenv, fetchFromGitHub, cmake, asciidoc, libxslt }:
 
 stdenv.mkDerivation rec {
   pname = "kpack";
@@ -12,9 +12,9 @@ stdenv.mkDerivation rec {
     sha256 = "1l6bm2j45946i80qgwhrixg9sckazwb5x4051s76d3mapq9bara8";
   };
 
-  nativeBuildInputs = [ cmake ];
+  strictDeps = true;
 
-  buildInputs = [ asciidoc libxslt.bin docbook_xsl ];
+  nativeBuildInputs = [ asciidoc cmake libxslt.bin ];
 
   hardeningDisable = [ "fortify" ];