BUG: Examples should build if BUILD_TESTING is OFF

With BUILD_EXAMPLES:ON and BUILD_TESTING:OFF, the Examples should
compile.

To configure VTK with BUILD_EXAMPLES:ON and BUILD_TESTING:OFF, from an
empty build tree,

cmake  -DBUILD_TESTING:BOOL=OFF -DCMAKE_BUILD_TYPE:STRING=Release vtk_src_tree

NOTE: If you have already configured VTK with default settings, you
must clean the build tree and rerun cmake with the above
setting. Otherwise, bogus tests will remain.

Change-Id: I2035e49c7df4ba6f3d88447ea1b768ec63b87ee7
Merge topic 'ExamplesWithoutTesting' into master

3c68fe1f BUG: Examples should build if BUILD_TESTING is OFF