OpenCL fallback to CPU device causes assert in debug build

[pezcode]

When the OpenCL backend falls back from GPU to CPU device, the following line causes an assert:

basis_universal/encoder/basisu_opencl.cpp

Line 111 in 6775d33

ocl_error_printf("ocl::init: Couldn't get any GPU device ID's, trying CL_DEVICE_TYPE_CPU\n");

ocl_error_printf() contains the following:

#if BASISU_OPENCL_ASSERT_ON_ANY_ERRORS
		assert(0);
#endif

even though in this case the error isn't fatal and execution continues normally in release builds.

BASISU_OPENCL_ASSERT_ON_ANY_ERRORS is hardcoded to 1 further up top so can't be disabled. The CPU device fallback should either not call ocl_error_printf() or BASISU_OPENCL_ASSERT_ON_ANY_ERRORS should be overridable, e.g.:

#ifndef BASISU_OPENCL_ASSERT_ON_ANY_ERRORS
  #define BASISU_OPENCL_ASSERT_ON_ANY_ERRORS (1)
#endif

[richgel999]

Thanks - will reproduce and fix.