re-add pipe::read impl to libst2.
rustc::middle::borrowck::gather_loans::lifetime: revise debug instrumentation.
rustc::middle::typeck::infer::region_inference add more debug instrumentation.
rustc::middle::typeck::check::dropck remove source of ReFunction.

includes debug output noting that we could have produced ReFunction here.
rustc::middle::region local check for trivial cyclic encl region scope.
rustc::middle::region added debug instrumentation to `fn ancestors_of`.
rustc::middle::region attempt to introduce CodeExtent::Closure and
CodeExtent::Misc differentiation.