bugfix: Fix regression on older android versions.

Introduced in commit
ffc4a15a890a348a28bf2438fb0f543eeccef74d

The call to setFormat( SurfaceHolder.SURFACE_TYPE_GPU ) was included in
a bunch of NVIDIA examples, but is deprecated now... probably for a
reason :P.  This breaks something in my Xperia PLAY running Android
2.3.3.  My bad sneaking a functional change into refactoring commit....