BUG: Fix memory leaks in MINCImageIO

This resolves Coverity CIDs: 1125948, 1125949, 1125950, 1125951.

Change-Id: Ic896a4286eab3a269dfca0c56bcab0bf090e7b6b
Merge topic 'coverity_cid_1125951'

2c8f681 BUG: Fix memory leaks in MINCImageIO