BUG: Remove -Wno-unused-local-typedefs flag.

This flag was used to remove false positive warnings from GCC due to
ConceptChecking on the ITK tests.  However, it did not mask the false positive
warnings for projects that link against ITK.

Commit

  8329f68

fixed the warnings without requiring a flag.  Remove the compiler flag.

Change-Id: Ia1ec42564b2437921e5e0c8efe628aa3ae91f4d9
Suggested-by: Jean-Christophe Fillion-Robin <jchris.fillionr@kitware.com>
Merge topic 'LocalTypedefsFlag'

29c2c7c2 BUG: Remove -Wno-unused-local-typedefs flag.