libcore: use unboxed closures in the fields of `Map`
libcollections: fix fallout
librustrt: fix fallout
libstd: fix fallout
libsyntax: fix fallout
librustc: fix fallout
librustc_trans: fix fallout
libcore: use unboxed closures in the fields of `Filter`
libunicode: fix fallout
librustc_trans: fix fallout
libcore: use unboxed closures in the fields of `FilterMap`
libcollections: fix fallout
libstd: fix fallout
librustdoc: fix fallout
libcore: use unboxed closures in the fields of `SkipWhile`
libcore: use unboxed closures in the fields of `TakeWhile`
libcore: use unboxed closures in the fields of `Scan`
libcore: use unboxed closures in the fields of `FlatMap`
libcore: use unboxed closures in the fields of `Inspect`
libcoretest: fix fallout