Disabled toHash in -betterC for now

TypeInfo is part of DRuntime.
See: #5952

Replaced `toHash` with a parameter-less template for codegen on demand.

Author: wilzbach

std/typecons.d

@@ -1135,12 +1135,20 @@ if (distinctFieldNames!(Specs))
             Returns:
                 A `size_t` representing the hash of this `Tuple`.
          */
-        size_t toHash() const nothrow @trusted
+        size_t toHash()() const nothrow @trusted
         {
-            size_t h = 0;
-            foreach (i, T; Types)
-                h += typeid(T).getHash(cast(const void*)&field[i]);
-            return h;
+            version(D_BetterC)
+            {
+                // Disabled in -betterC for now as TypeInfo isn't present
+                static assert (0, "Not implemented");
+            }
+            else
+            {
+                size_t h = 0;
+                foreach (i, T; Types)
+                    h += typeid(T).getHash(cast(const void*)&field[i]);
+                return h;
+            }
         }
 
         ///