clSetKernelArg arg_value for pointers to the local address space error condition

[bashbaug]

The current description of clSetKernelArg says:

If the argument is declared with the local qualifier, the arg_value entry must be NULL.

However, there is no documented error condition if arg_value is not equal to NULL.

Should this be CL_INVALID_VALUE (see: #1493 (comment)) or something else?

Since this is another new error condition, it may need to be added as part of an extension or a new minor OpenCL version.