Fix nan errors when using VehicleBody

(cherry picked from commit 1b8cbcf94648b7baeb3def5464f6f67509081134)

scene/3d/vehicle_body.cpp

@@ -389,6 +389,7 @@ VehicleWheel::VehicleWheel() {
 	m_suspensionRelativeVelocity = 0;
 	m_clippedInvContactDotSuspension = 1.0;
 	m_raycastInfo.m_isInContact = false;
+	m_raycastInfo.m_suspensionLength = 0.0;
 
 	body = NULL;
 }