BUG:11947 plug memory leaks in vtkSelectPolyData exceptions

Thanks Xabi Riobe for the patch.

Change-Id: Ie1fe74a12a67234c752fd02263c6d5df7b759d4b
Fix logic in GPUVolumeRayCastMapper GL support test

The logic was failing cards that had support, using
the extension manager un-initialized, and not reporting
the specifc reason for failure. This patch fixes these
issues.

Change-Id: If31d66e304cdea81e09a5db08726587fbc0853e0
Merge topic 'gpu-raycast-mapper-error-report' into master

4212d0af Fix logic in GPUVolumeRayCastMapper GL support test
Merge topic '0011947-selectpolydata-mem-leak' into master

a9743934 BUG:11947 plug memory leaks in vtkSelectPolyData exceptions