Update IFCReaderGen_2x3.h

Fix a typo

code/Importer/IFC/IFCReaderGen_2x3.h

@@ -46,7 +46,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "code/Step/STEPFile.h"
 
 #ifdef _WIN32
-#    pragma warning( disable 4512 )
+#    pragma warning( disable : 4512 )
 #endif // _WIN32
 
 namespace Assimp {