change distance result brief information to intptr_t

The distance result brief information stored the brief information
in an `int`. However, some primatives can only be stored by pointer
(namely octree nodes), and `int` is not wide enough on 64-bit
platforms to safely store a pointer. So upgrade the brief
information to be `intptr_t` which is guaranteed to be wide enough.

include/fcl/common/types.h

@@ -60,6 +60,8 @@ using int64 = std::int64_t;
 using uint64 = std::uint64_t;
 using int32 = std::int32_t;
 using uint32 = std::uint32_t;
+using intptr_t = std::intptr_t;
+using uintptr_t = std::uintptr_t;
 
 template <typename S>
 using Vector2 = Eigen::Matrix<S, 2, 1>;

include/fcl/narrowphase/distance_result.h

@@ -78,13 +78,13 @@ struct FCL_EXPORT DistanceResult
   /// if object 1 is mesh or point cloud, it is the triangle or point id
   /// if object 1 is geometry shape, it is NONE (-1),
   /// if object 1 is octree, it is the id of the cell
-  int b1;
+  intptr_t b1;
 
   /// @brief information about the nearest point in object 2
   /// if object 2 is mesh or point cloud, it is the triangle or point id
   /// if object 2 is geometry shape, it is NONE (-1),
   /// if object 2 is octree, it is the id of the cell
-  int b2;
+  intptr_t b2;
 
   /// @brief invalid contact primitive information
   static const int NONE = -1;