kernel: slight refactor, add warnings about new kernels, and known limitations of zuikkis.

Limitations of alexkar* kernels are not known to me.

Closes https://github.com/veox/sgminer/issues/28

ocl.c

@@ -415,30 +415,32 @@ _clState *initCl(unsigned int gpu, char *name, size_t nameSize)
 	else if (preferred_vwidth > 2)
 		preferred_vwidth = 2;
 
+	/* All available kernels only support vector 1 */
+	cgpu->vwidth = 1;
+
 	switch (clState->chosen_kernel) {
 		case KL_ALEXKARNEW:
+			applog(LOG_WARNING, "Kernel alexkarnew is experimental.");
 			strcpy(filename, ALEXKARNEW_KERNNAME".cl");
 			strcpy(binaryfilename, ALEXKARNEW_KERNNAME);
-			/* Kernel only supports vector 1 */
-			cgpu->vwidth = 1;
 			break;
 		case KL_ALEXKAROLD:
+			applog(LOG_WARNING, "Kernel alexkarold is experimental.");
 			strcpy(filename, ALEXKAROLD_KERNNAME".cl");
 			strcpy(binaryfilename, ALEXKAROLD_KERNNAME);
-			/* Kernel only supports vector 1 */
-			cgpu->vwidth = 1;
 			break;
 		case KL_CKOLIVAS:
 			strcpy(filename, CKOLIVAS_KERNNAME".cl");
 			strcpy(binaryfilename, CKOLIVAS_KERNNAME);
-			/* Kernel only supports vector 1 */
-			cgpu->vwidth = 1;
 			break;
 		case KL_ZUIKKIS:
+			applog(LOG_WARNING, "Kernel zuikkis is experimental.");
 			strcpy(filename, ZUIKKIS_KERNNAME".cl");
 			strcpy(binaryfilename, ZUIKKIS_KERNNAME);
-			/* Kernel only supports vector 1 */
-			cgpu->vwidth = 1;
+			/* Kernel only supports lookup-gap 2 */
+			cgpu->lookup_gap = 2;
+			/* Kernel only supports worksize 256 */
+			cgpu->work_size = 256;
 			break;
 		case KL_NONE: /* Shouldn't happen */
 			break;