neovim: improve lpeg patch for darwin

pkgs/by-name/ne/neovim-unwrapped/package.nix

@@ -33,18 +33,26 @@ stdenv.mkDerivation (
     nvim-lpeg-dylib =
       luapkgs:
       if stdenv.hostPlatform.isDarwin then
+        let
+          luaLibDir = "$out/lib/lua/${lib.versions.majorMinor luapkgs.lua.luaversion}";
+        in
         (luapkgs.lpeg.overrideAttrs (oa: {
           preConfigure = ''
             # neovim wants clang .dylib
             sed -i makefile -e "s/CC = gcc/CC = clang/"
             sed -i makefile -e "s/-bundle/-dynamiclib/"
+            sed -i makefile -e "s/lpeg.so/lpeg.dylib/"
+            sed -i makefile -e '/^linux:$/ {N; d;}'
           '';
           preBuild = ''
             # there seems to be implicit calls to Makefile from luarocks, we need to
             # add a stage to build our dylib
             make macosx
-            mkdir -p $out/lib
-            mv lpeg.so $out/lib/lpeg.dylib
+            mkdir -p ${luaLibDir}
+            mv lpeg.dylib ${luaLibDir}/lpeg.dylib
+          '';
+          postInstall = ''
+            rm -f ${luaLibDir}/lpeg.so
           '';
           nativeBuildInputs =
             oa.nativeBuildInputs ++ (lib.optional stdenv.hostPlatform.isDarwin fixDarwinDylibNames);