lua-lpeg inheritance fix (#49065)

The parent class function doesn't return the path to the config file. This is one potential fix, or we can add the return back to base builder.

var/spack/repos/builtin/packages/lua-lpeg/package.py

@@ -47,7 +47,8 @@ class LuaBuilder(spack.build_systems.lua.LuaBuilder):
     # * replaces `-bundle` from the default flags with `-shared`
     @when("platform=darwin")
     def generate_luarocks_config(self, pkg, spec, prefix):
-        path = super().generate_luarocks_config(pkg, spec, prefix)
+        super().generate_luarocks_config(pkg, spec, prefix)
+        path = self._luarocks_config_path()
 
         with open(path, "a") as cfg:
             cfg.write(