opencl: Add "goffset" setting to override detection of support for global work offsets
opencl: Determine kernel support for goffset by code analysis
opencl: Add no-goffset support to scrypt kernels
opencl: Autodetect whether global offset actually works
opencl: Remove support for "OCL1" kernel define (indicated OpenCL 1.1+)
Merge branch 'ocl_opt_goffset' into bfgminer