st/nine: Silent warning in NineCubeTexture9_ctor
st/nine: Silent warning in NineCubeTexture9_ctor

The compiler was complaining the value may be uninitialised
when it is used (which is wrong). Initialize to NULL to silent
the warning.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler