Cleanup: sync map_to_sphere, UNLIKELY xy zero case

intern/cycles/util/util_math.h

@@ -1419,10 +1419,12 @@ ccl_device bool map_to_sphere(float *r_u, float *r_v,
 {
 	float len = sqrtf(x * x + y * y + z * z);
 	if(len > 0.0f) {
-		if(x == 0.0f && y == 0.0f)
+		if(UNLIKELY(x == 0.0f && y == 0.0f)) {
 			*r_u = 0.0f;  /* othwise domain error */
-		else
+		}
+		else {
 			*r_u = (1.0f - atan2f(x, y) / M_PI_F) / 2.0f;
+		}
 		*r_v = 1.0f - safe_acosf(z / len) / M_PI_F;
 		return true;
 	}