selsnap: simplify SNAP_LINE case

Also make sure y never exceeds term.row-1 even if ATTR_WRAP is set for
some reason.

st.c

@@ -772,15 +772,15 @@ selsnap(int *x, int *y, int direction) {
 		 * previous line will be selected.
 		 */
 		*x = (direction < 0) ? 0 : term.col - 1;
-		if(direction < 0 && *y > 0) {
+		if(direction < 0) {
 			for(; *y > 0; *y += direction) {
 				if(!(term.line[*y-1][term.col-1].mode
 						& ATTR_WRAP)) {
 					break;
 				}
 			}
-		} else if(direction > 0 && *y < term.row-1) {
+		} else if(direction > 0) {
-			for(; *y < term.row; *y += direction) {
+			for(; *y < term.row-1; *y += direction) {
 				if(!(term.line[*y][term.col-1].mode
 						& ATTR_WRAP)) {
 					break;