Fixed an inconsistent use of pointers in 64 bit case in dataset creation

[JoeNemo]

Proposed changes

64 bit pointers to arrays of pointers to text units were inconsistently defined.

This PR addresses Issue:

#388

This PR depends upon the following PRs:

Type of change

Please delete options that are not relevant.

• [ x] Bug fix (non-breaking change which fixes an issue)

PR Checklist

Please delete options that are not relevant.

• [ x] If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• [ x] My code follows the style guidelines of this project (see: Contributing guideline)
• [ x] I have added tests that prove my fix is effective or that my feature works, or describe a test method below

Testing

There is a test in zowe-common-c/tests/datasetCreate.c with test data in tests/create1.json. There are instructions at the top of that file.