Fix incorrectly qualified return type from unique_ptr::get_deleter().

For reference deleter types the const qualifier on the return type
of get_deleter() should be ignored, and a non-const deleter should
be returned.

This patch fixes a bug where "const deleter_type&" is incorrectly
formed.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@300121 91177308-0d34-0410-b5e6-96231b3b80d8

test/support/test_macros.h

@@ -184,7 +184,7 @@ struct is_same<T, T> { enum {value = 1}; };
 } // namespace test_macros_detail
 
 #define ASSERT_SAME_TYPE(...) \
-    static_assert(test_macros_detail::is_same<__VA_ARGS__>::value, \
+    static_assert((test_macros_detail::is_same<__VA_ARGS__>::value), \
                  "Types differ uexpectedly")
 
 #ifndef TEST_HAS_NO_EXCEPTIONS