collections: remove List

It was decided in a meeting that this module wasn't needed,
and more thought should be put into a persistent collections
library.
test: remove pure test, which is now redundant with inline tests
std and green: fix some warnings
auto merge of #13183 : erickt/rust/remove-list, r=alexcrichton

`collections::list::List` was decided in a [team meeting](https://github.com/mozilla/rust/wiki/Meeting-weekly-2014-03-25) that it was unnecessary, so this PR removes it. Additionally, it removes an old and redundant purity test and fixes some warnings.
configure: Add MINGW64 OS type

MSYS2 supports `MINGW64` system for 64-bit environment. It sets
`MSYSTEM=MINGW64` environment variable, which changes output of
`uname -s` thus affects `configure` behavior.

This patch adds `MINGW64*` support for `configure`.
auto merge of #13199 : klutzy/rust/msys2, r=cmr

MSYS2 supports `MINGW64` system for 64-bit environment. It sets
`MSYSTEM=MINGW64` environment variable, which changes output of
`uname -s` thus affects `configure` behavior.

This patch adds `MINGW64*` support for `configure`.
Use new inner attribute syntax in test framework
auto merge of #13200 : sfackler/rust/test-attr, r=cmr
Removed deprecated functions `map` and `flat_map` for vectors and slices.
auto merge of #13203 : Kimundi/rust/de-map-vec3, r=cmr

They required unnecessary temporaries, are replaced with iterators, and would conflict with a possible future `Iterable` trait.