50% performance gain on GCN for sha512crypt. Recommended for (at least) 12.08 Catalyst driver

....

From:
  Local work size (LWS) 64, global work size (GWS) 16384
  Benchmarking: sha512crypt (rounds=5000) [OpenCL]... DONE
  Raw:	8316 c/s real, 409600 c/s virtual

To:
  Local work size (LWS) 64, global work size (GWS) 16384
  Benchmarking: sha512crypt (rounds=5000) [OpenCL]... DONE
  Raw:	12603 c/s real, 546133 c/s virtual