[svn-r12185] Purpose: Code cleanup

Description:
    Removed an empty #ifdef block that was left by mistake.

Platforms tested:
    Linux 2.4 (heping) - very minor

c++/src/H5DxferProp.cpp

@@ -13,8 +13,6 @@
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
 #include <string>
-#ifndef H5_NO_NAMESPACE
-#endif
 
 #include "H5Include.h"
 #include "H5Exception.h"