Update _tri.cpp

added empty line at end

Author: tybeller

src/tri/_tri.cpp

@@ -2056,4 +2056,4 @@ TrapezoidMapTriFinder::Trapezoid::set_upper_right(Trapezoid* upper_right_)
     upper_right = upper_right_;
     if (upper_right != 0)
         upper_right->upper_left = this;
-}
+}