(this is number 6 of 9 commits to be applied together)

  It is useful to know the usage of a lambda outside the usage
  inference (specifically, in the simplifier); thus as a temporary
  hack to make this information available without undue modification
  to the rest of the compiler, the information is copied into the
  IdInfo field of the binder.

  The new information is LBVarInfo, which can be either NoLBVarInfo or
  IsOneShotLambda, corresponding to __m/no info and __o respectively.
  LBVarInfo is not intended to be printed in interface files; to
  enforce this ppLBVarInfo is defined to print nothing.