rend.c: Fix __imlib_generic_render() when jump != 0

Patch by the_third.

https://phab.enlightenment.org/T8799

src/lib/rend.c

@@ -227,6 +227,7 @@ __imlib_generic_render(DATA32 * src, int jump, int w, int h, int dx, int dy,
              XPutPixel(xim, x, y, val);
              src++;
           }
+        src += jump;
      }
 }