Release() and recreate the depth-stencil surface when resetting the D3D9 driver. This surface is implicitly created with D3DPOOL_DEFAULT, so needs to be released or the reset fails.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1759 dfc29bdd-3216-0410-991c-e03cc46cb475