temporary fix for cmake cross-compilation

overlay.nix

@@ -77,6 +77,22 @@ extraPkgs // {
 
     };
 
+  # luarocks wants a cross-compiled cmake (which seems like a bug,
+  # we're never going to run luarocks on the device, but ...)
+  # but https://github.com/NixOS/nixpkgs/issues/284734
+  # so we do surgery on the cmake derivation until that's fixed
+
+  cmake = prev.cmake.overrideAttrs(o:
+    # don't override the build cmake or we'll have to rebuild
+    # half the known universe to no useful benefit
+    if final.stdenv.buildPlatform != final.stdenv.hostPlatform
+    then {
+      preConfigure =
+        builtins.replaceStrings
+          ["$configureFlags"] ["$configureFlags $cmakeFlags"] o.preConfigure;
+    }
+    else {}
+  );
 
   dnsmasq =
     let d =  prev.dnsmasq.overrideAttrs(o: {