BGE: Fix for [#34383] Blender crash Steering actuator 2.66 -> 2.59 -> 2.66. Reported and fixed by HG1.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56353 954f8c5b-7b00-dc11-b283-0030488c597c