Fixed OpenCL initialization to be slightly more robust.
Fixed OpenCL initialization to be slightly more robust.

On platforms with multiple devices (e.g. OS X Mavericks
with both Intel and Discrete GPU CL devices) we must
create the context and command queue with the correct
device in order to share resources with GL.

nyotis/OpenSubdiv,shengfuintel/OpenSubdiv,nyotis/OpenSubdiv,takahito-tejima/OpenSubdiv,anshuarya/OpenSubdiv,c64kernal/OpenSubdiv,lookup1980/OpenSubdiv,xldeveloper/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,xldeveloper/OpenSubdiv,anshuarya/OpenSubdiv,nyotis/OpenSubdiv,poljere/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,shengfuintel/OpenSubdiv,shengfuintel/OpenSubdiv,takahito-tejima/OpenSubdiv,jcowles/OpenSubdiv,anshuarya/OpenSubdiv,takahito-tejima/OpenSubdiv,lookup1980/OpenSubdiv,c64kernal/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,xldeveloper/OpenSubdiv,lookup1980/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,c64kernal/OpenSubdiv,poljere/OpenSubdiv,poljere/OpenSubdiv,jcowles/OpenSubdiv,jcowles/OpenSubdiv