2X unroll loop

From 37167 to 38621 lines per second on RP2040-GEEK.

Author: tuupola

src/hagl_line.c

@@ -67,9 +67,27 @@ void hagl_draw_line(
     while (1) {
         surface->put_pixel((void *)_surface, x0, y0, color);
 
-        if (x0 == x1 && y0 == y1) {
+        if ((x0 == x1) && (y0 == y1)) {
             break;
-        };
+        }
+
+        e2 = err + err;
+
+        if (e2 > -dx) {
+            err -= dy;
+            x0 += sx;
+        }
+
+        if (e2 < dy) {
+            err += dx;
+            y0 += sy;
+        }
+
+        surface->put_pixel((void *)_surface, x0, y0, color);
+
+        if ((x0 == x1) && (y0 == y1)) {
+            break;
+        }
 
         e2 = err + err;