Fix in friend declarations.

[SVN r18661]

include/boost/aligned_storage.hpp

@@ -67,14 +67,14 @@ public: // constants
 
 private: // representation
 
-    friend union data_t;
-
     union data_t
     {
         char buf[size];
         align_t dummy_;
     } data_;
 
+    friend union data_t;
+
 #if BOOST_WORKAROUND(__GNUC__, BOOST_TESTED_AT(2))
 
 public: // _should_ be noncopyable, but GCC compiler emits error