Add missing filesystem hash function... again

engine/utility/include/path.hpp

@@ -1,7 +1,18 @@
 #pragma once
 
 #include <filesystem>
+#include <optional>
 
 namespace prism {
     using path = std::filesystem::path;
 }
+
+// some stdlibs such as apple's clang fail to provide this :-/
+namespace std {
+    template <>
+    struct hash<prism::path> {
+        std::size_t operator()(const prism::path& k) const {
+            return (std::hash<std::string>()(k.string()));
+        }
+    };
+}