Add support in the fullsys script to run the POVray benchmark.

To run it use
-ETEST=POVRAY_BENCH   to run the built in povray benchmark program (more CPU intensive, small fileset ~11MB)
-ETEST=POVRAY_AUTUMN  to run the first part of a rendering of a autumn leaves/tree scene, less cpu intensive ~500MB working set.

For now I have been running with -ESYSTEM=Simple in order to drop checkpoints (built into binary at the point the render begins) and create memory traces.
I will check in a SYSTEM=3D_DRAM and SYSTEM=3D_CACHE configuration as soon as those are ready.

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extra : convert_revision : fb55834a02317d5e9961a5145c932965c8bc6a0e