Fixing a null argument to 'strdup' per e-mail from Eero Pajarre dated 6/8/2011 4:15 AM

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@926 7f0cb862-5218-0410-a997-914c9d46530a

freeglut/freeglut/src/freeglut_init.c

@@ -314,7 +314,7 @@ static void fghInitialize( const char* displayName )
 
     /* What we need to do is to initialize the fgDisplay global structure here. */
     fgDisplay.Instance = GetModuleHandle( NULL );
-    fgDisplay.DisplayName=strdup(displayName);
+    fgDisplay.DisplayName= displayName ? strdup(displayName) : 0 ;
     atom = GetClassInfo( fgDisplay.Instance, _T("FREEGLUT"), &wc );
 
     if( atom == 0 )