Add mipmap generation for makeColorKeyTexture

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@4285 dfc29bdd-3216-0410-991c-e03cc46cb475

source/Irrlicht/CNullDriver.cpp

@@ -1066,6 +1066,7 @@ void CNullDriver::makeColorKeyTexture(video::ITexture* texture,
 
 		texture->unlock();
 	}
+	texture->regenerateMipMapLevels();
 }