BUG: Fix for test pvcs.GMVReaderBasicRead-static failing on 64-bit Linux

Using vtkTypeInt64Array instead of vtkLongArray to use fixed width array for
better portability.

Change-Id: I54db0c5757209e1c8a0adcd10029b59f3378f772
Merge topic '13688_fix_gmv_reader_issues' into next

88c10fa BUG: Fix for test pvcs.GMVReaderBasicRead-static failing on 64-bit Linux