Moved core::extfmt to core::private::extfmt

Needs a snapshot to remove stage0 extfmt export in core
Remove the last bits of structural records from tests/rustc/rusti/rustpkg.
librustc: De-mut resolve. rs=demuting
librustc: De-mut some of trans
librustc: De-mut trans. rs=demuting
librustc: Remove all mutable fields from librustc. rs=demuting
Cleanup, commenting, trivial renaming
bump up limit on monomorphization
librustc: Fix broken test.
auto merge of #5059 : Kimundi/rust/incoming, r=catamorphism

compiles-as-is, but needs a snapshot to remove the `stage0`ed extfmt export in core.

Closes #4750
auto merge of #5075 : luqmana/rust/derec, r=catamorphism

Now only `lib core/pipes.rs` has `#[allow(structural_records)]`. That can be removed after a snapshot.
auto merge of #5076 : pcwalton/rust/demuting, r=pcwalton
auto merge of #5077 : jbclements/rust/increase-monomorphization-depth-limit, r=catamorphism

It appears that using deriving_eq/auto_encode on ASTs bumps up against the "gee this looks like infinite unfolding" limit of 10 in monomorphization. Increasing it to 30 seems to solve this problem for me....

Also, commenting and a few renames.
mk: Restructure makefiles to distinguish between host and target triples
Android Makefile Transition in progress
Android Makefile Transition in progress2
Android Makefile Transition in progress3
update libuv android
update libuv android2
lastest follow up