Get rid of some warnings, mainly unused parameters/variables.

Thanks sparkprime for the patch, see http://code.google.com/p/bullet/issues/detail?id=330

src/BulletDynamics/ConstraintSolver/btSolverBody.h

@@ -168,6 +168,7 @@ ATTRIBUTE_ALIGNED16 (struct)	btSolverBody
 
 	void	writebackVelocity(btScalar timeStep)
 	{
+        (void) timeStep;
 		if (m_originalBody)
 		{
 			m_originalBody->setLinearVelocity(m_originalBody->getLinearVelocity()+ m_deltaLinearVelocity);

src/BulletDynamics/ConstraintSolver/btTypedConstraint.h

@@ -104,6 +104,10 @@ public:
 	///internal method used by the constraint solver, don't use them directly
 	virtual	void	setupSolverConstraint(btConstraintArray& ca, int solverBodyA,int solverBodyB, btScalar timeStep)
 	{
+        (void)ca;
+        (void)solverBodyA;
+        (void)solverBodyB;
+        (void)timeStep;
 	}
 	
 	///internal method used by the constraint solver, don't use them directly