OCTTransform and OCTTransformEx do not check for NULL pointer

[Leith Bade]

I discovered a bug in OCTTransform and OCTTransformEx.

The functions do not check if hTransform is NULL before they call hTransform->Transform() .

As such if the caller passes in NULL (say because creating the coordinate transformation failed on some previous step) the program crashes.

I have attached a patch against latest SVN trunk.

I the code compiles but I was not able to autotest it as trunk autotest was crashing my Python.

[Leith Bade]

Patch for ogrct.cpp