add alignment for broadphase proxy/handle. need to benchmark this, and check it doesn't degrade the performance on other platforms. Otherwise make it conditional only when USE_LIBSPE2 is defined

src/BulletCollision/BroadphaseCollision/btAxisSweep3.h

@@ -51,9 +51,10 @@ public:
 	};
 
 public:
-	class Handle : public btBroadphaseProxy
+	ATTRIBUTE_ALIGNED16(class) Handle : public btBroadphaseProxy
 	{
 	public:
+	BT_DECLARE_ALIGNED_ALLOCATOR();
 	
 		// indexes into the edge arrays
 		BP_FP_INT_TYPE m_minEdges[3], m_maxEdges[3];		// 6 * 2 = 12

src/BulletCollision/BroadphaseCollision/btBroadphaseProxy.h

@@ -17,6 +17,7 @@ subject to the following restrictions:
 #define BROADPHASE_PROXY_H
 
 #include "LinearMath/btScalar.h" //for SIMD_FORCE_INLINE
+#include "LinearMath/btAlignedAllocator.h"
 
 
 /// btDispatcher uses these types
@@ -63,9 +64,11 @@ CONCAVE_SHAPES_END_HERE,
 
 
 ///btBroadphaseProxy
-struct btBroadphaseProxy
+ATTRIBUTE_ALIGNED16(struct) btBroadphaseProxy
 {
 
+BT_DECLARE_ALIGNED_ALLOCATOR();
+	
 	///optional filtering to cull potential collisions
 	enum CollisionFilterGroups
 	{
@@ -137,7 +140,7 @@ struct btBroadphaseProxy;
 
 
 /// contains a pair of aabb-overlapping objects
-struct btBroadphasePair
+ATTRIBUTE_ALIGNED16(struct) btBroadphasePair
 {
 	btBroadphasePair ()
 		:
@@ -148,6 +151,8 @@ struct btBroadphasePair
 	{
 	}
 
+BT_DECLARE_ALIGNED_ALLOCATOR();
+
 	btBroadphasePair(const btBroadphasePair& other)
 		:		m_pProxy0(other.m_pProxy0),
 				m_pProxy1(other.m_pProxy1),