rt: Remove rust_env
Remove the annihilate lang item
rt: Remove rust_signal.h
rt: Remove unused parts of rust_globals.h
rt: Remove unused parts of rust_log
rt: Remove rust_refcount.h
rt: Remove rust_stack
rt: Remove unused rust_clone_type_desc declaration
rt: Remove empty rust_upcall.h
rt: Remove unused uv helpers
Fix warnings in tests
Fix warnings in librustc and libsyntax
Fix warnings it tests
Deny warnings in stage1+ libsyntax/librustc/librustdoc/librusti/librust
auto merge of #8441 : erickt/rust/deny-warnings, r=erickt

This patch makes sure that code is warning-free for all of the rust libraries.
auto merge of #8433 : brson/rust/rm-more-oldrt-crud, r=brson

Just deleting more stuff.
remove the Times trait in favour of `range`

It's not possible to break from `times` and it results in the
restrictions coming from closures. Using `for _ in range(0, n)` from the
start is simpler, rather than switching to it after hitting either of
these issues.