Blender Git Loki

Change class hierarchy in device_opencl.cpp and refactor

Class hierarchy change :
The new class hierarchy is as follows,
OpenCLDeviceBase (inherits Device) - Contains error-handlers, texture functiions and other
common functions between MegaKernel and SplitKernel
OpenCLDeviceSplitKernel (inherits OpenCLDeviceBase) - Contains variables and functions specific to
split kernel implementation
OpenCLDeviceMegaKernel (inherits OpenCLDeviceBase) - Contains variables and functions specific to
megakernel
Refactor :
Change "if " to "if"