kicad: remove gettext from buildInputs, add to nativeBuildInputs

The i18n "library" does not link against gettext. It only requires the
msgfmt utility from gettext, hence gettext should be a nativeBuildInput

pkgs/applications/science/electronics/kicad/libraries.nix

@@ -62,8 +62,7 @@ in
           inherit name;
         } // (libSources.${name} or { })
       );
-      buildInputs = [ gettext ];
-      nativeBuildInputs = [ cmake ];
+      nativeBuildInputs = [ cmake gettext ];
       meta = {
         license = licenses.gpl2; # https://github.com/KiCad/kicad-i18n/issues/3
         platforms = stdenv.lib.platforms.all;