Remove incorrect comment

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonContext.java

@@ -808,7 +808,6 @@ public Thread getOwner() {
     // the full module name for package imports
     private TruffleString pyPackageContext;
 
-    // the actual pointer will be set when the cext is initialized
     private final NativePointer nativeNull = NativePointer.createNull();
 
     public RootCallTarget signatureContainer;