OpenGEXImporter: Fix IOStream leak

code/OpenGEXImporter.cpp

@@ -307,6 +307,7 @@ void OpenGEXImporter::InternReadFile( const std::string &filename, aiScene *pSce
 
     std::vector<char> buffer;
     TextFileToBuffer( file, buffer );
+    pIOHandler->Close( file );
 
     OpenDDLParser myParser;
     myParser.setBuffer( &buffer[ 0 ], buffer.size() );