update command buffer samples and emulation layer

[bashbaug]

There were some breaking changes recently in the command buffer specifications and hence the headers:

• Use array for clUpdateMutableCommandsKHR. KhronosGroup/OpenCL-Docs#1045
• Add properties parameter to all command-buffer commands KhronosGroup/OpenCL-Docs#1215

These require updates to the command buffer samples and the emulation layer.