Fix memory leak when image accessor fails to construct

Make sure to free any already allocated memory before allowing an
exception to propagate out of the constructor because the destructor
will not be called on the non-completely-constructed ImageReadAccessor
object.

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Fix memory leak when creating a ImageReadAccessor with IgnoreLock enabled

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Fix leaks found by running non-rendering unit tests with VTK_DEBUG_LEAKS

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Merge branch 'bug-16674-fix-memory-leaks-ImageReadAccessor'

* bug-16674-fix-memory-leaks-ImageReadAccessor:
  Fix memory leak when creating a ImageReadAccessor with IgnoreLock enabled
  Fix memory leak when image accessor fails to construct
Merge branch 'bug-16674-fix-memory-leaks-VTK_DEBUG_LEAKS'

* bug-16674-fix-memory-leaks-VTK_DEBUG_LEAKS:
  Fix leaks found by running non-rendering unit tests with VTK_DEBUG_LEAKS