fix compilation issue with recent compilers
cfr. https://sourceforge.net/p/esmf/esmf/ci/3706bf758012daebadef83d6575c477aeff9c89b/#diff-1
--- src/Infrastructure/Mesh/src/Moab/io/ReadABAQUS.cpp.orig	2017-04-19 13:44:03.384547426 +0200
+++ src/Infrastructure/Mesh/src/Moab/io/ReadABAQUS.cpp	2017-04-19 13:44:16.864674576 +0200
@@ -105,7 +105,7 @@
 ReadABAQUS::~ReadABAQUS() 
 {
   mdbImpl->release_interface(readMeshIface);
-  if (NULL != abFile)
+  if (abFile.is_open())
     abFile.close();
 }
 
