To enable the AMD APP SDK tests:

1) run 'make AMD-APP-SDK-v2.8-RC-lnx64.tgz' to download the SDK
2) configure pocl, it should now detect the AMD benchmark and
   enable it
3) call 'make check TESTSUITEFLAGS="-k amdsdk"', it should build 
   the AMD cases and run the pocl test suite for the AMD SDK.

After this you can run tools/scripts/benchmark.py to produce
performance numbers.

