luaPackages.luaossl: fixup build with gcc15

https://hydra.nixos.org/build/317380691/nixlog/2/tail
(same for all lua*Packages)

pkgs/development/lua-modules/overrides.nix

@@ -589,7 +589,7 @@ in
     '';
   });
 
-  luaossl = prev.luaossl.overrideAttrs (_: {
+  luaossl = prev.luaossl.overrideAttrs (old: {
     externalDeps = [
       {
         name = "CRYPTO";
@@ -600,6 +600,10 @@ in
         dep = openssl;
       }
     ];
+
+    env = old.env // {
+      NIX_CFLAGS_COMPILE = "-Wno-error=incompatible-pointer-types"; # for gcc15
+    };
   });
 
   luaposix = prev.luaposix.overrideAttrs (_: {