In demo code, show CL_PROGRAM_BUILD_LOG if ccl_program_build fails

[shusheer]

Many folks will probably use the example code as the basis for their first projects - which will likely have bugs in kernels.

Make life easier for them by replacing eg. this code

	ccl_program_build(prg, NULL, &err);
	HANDLE_ERROR(err);

with this code:

	ccl_program_build(prg, NULL, &err);
	if (err != NULL)
	{
		CCLErr* err2 = NULL;
		fprintf(stderr, "\n%s\nBuild Error: Log Start\n", err->message);
		char* log = ccl_program_get_build_info_array(prg, dev, CL_PROGRAM_BUILD_LOG, char*, &err2);
		fprintf(stderr, "\n%s\nBuild Log End\n", log);
		HANDLE_ERROR(err2);
	}
	HANDLE_ERROR(err);