BUG #12753: Fixed support for large images.

We were running into overflow issues with the image dimensions are
large. Fixed that.

Change-Id: I0fd81828d1c780b384f39815f70171e3679819c9
BUG #11607: Fixed support for large images.

Similar to fix for BUG #12753, except this time fixing it for
vtkXMLPStructuredDataReader.

Change-Id: Iecc61616a628f04b428eba738a08c510e0f1cf4f
Merge topic '12753_fix_largefile_support' into master

51996a64 BUG #11607: Fixed support for large images.
4087b625 BUG #12753: Fixed support for large images.