Handling of void-Types added as in P0052R5.

include/unique_resource.h

         }
 
         template<class RR = R,
-            std::enable_if_t<std::is_pointer<RR>::value, int> = 0>
+            std::enable_if_t<( std::is_pointer<RR>::value && !std::is_void<std::remove_pointer_t<RR>>::value), int> = 0>
         std::add_lvalue_reference_t<std::remove_pointer_t<RR>> operator*() const noexcept
         {
             return *get();