Fix a bug when LGT and PVQ are both on.
Fixed a bug in my previous patch that causes a compile error (variable block undefined) when pvq is on. However, with or without LGT, --enable-pvq still has a run time error during encoding. This run time error is independent of the LGT experiment. Change-Id: I98ca5f69a916ea8556e45b820c2eb741c9656277