Removed forwarding resource and deleter when constructor may throw.

When resource_holder and deleter_holder are constructed, and resource/deleter
constructor may throw, remove forwarding the source resource/deleter to
the constructor. Forwarding there has no effect anyway, as the unique_resource
constructor already ensures the corresponding argument is passed as
an lvalue reference by using move_or_copy_construct_ref.

include/boost/scope/unique_resource.hpp

@@ -202,13 +202,13 @@ class resource_holder :
 
     template< typename R, typename D >
     explicit resource_holder(R&& res, D&& del, bool allocated, std::false_type) try :
-        resource_base(static_cast< R&& >(res))
+        resource_base(res)
     {
     }
     catch (...)
     {
         if (allocated)
-            del(static_cast< R&& >(res));
+            del(res);
     }
 };
 
@@ -280,13 +280,13 @@ class resource_holder< Resource, Traits, true > :
 
     template< typename R, typename D >
     explicit resource_holder(R&& res, D&& del, bool allocated, std::false_type) try :
-        resource_base(static_cast< R&& >(res))
+        resource_base(res)
     {
     }
     catch (...)
     {
         if (allocated)
-            del(static_cast< R&& >(res));
+            del(res);
     }
 };
 
@@ -357,7 +357,7 @@ class deleter_holder :
 
     template< typename D >
     explicit deleter_holder(D&& del, resource_type& res, bool allocated, std::false_type) try :
-        deleter_base(static_cast< D&& >(del))
+        deleter_base(del)
     {
     }
     catch (...)