fixw warnings (#299)

Author: minggo

poly2tri/common/shapes.h

@@ -57,7 +57,7 @@ struct Point {
   std::vector<Edge*> edge_list;
 
   /// Construct using coordinates.
-  Point(double x, double y) : x(x), y(y) {}
+  Point(double x_, double y_) : x(x_), y(y_) {}
 
   /// Set this point to all zeros.
   void set_zero()
@@ -320,4 +320,4 @@ inline void Triangle::IsInterior(bool b)
 
 }
 
-#endif
+#endif