Virtuozzo license versions enumeration.

enum _PRL_VERSION_ENUM {
  PRL_VERSION_ANY = 0,
  PRL_VERSION_3X = 1,
  PRL_VERSION_4X = 2,
  PRL_VERSION_5X = 3,
  PRL_VERSION_6X = 4,
  PRL_VERSION_7X = 5,
  PRL_VERSION_8X = 6,
  PRL_VERSION_9X = 7,
  PRL_VERSION_10X = 8
};