Upgrade LLVM for segmented stacks on thumb

This updates the LLVM submodule to the `rust-llvm-2014-02-19` tag which is the
old one with https://github.com/rust-lang/llvm/pull/4 cherry-picked on top.

Awesome job by @neykov for this!
Changed NonCamelCaseTypes lint to warn by default

Added allow(non_camel_case_types) to librustc where necesary

Tried to fix problems with non_camel_case_types outside rustc

fixed failing tests

Docs updated

Moved #[allow(non_camel_case_types)] a level higher.

markdown.rs reverted

Fixed timer that was failing tests

Fixed another timer
auto merge of #12407 : alexcrichton/rust/up-llvm, r=sfackler

This updates the LLVM submodule to the `rust-llvm-2014-02-19` tag which is the
old one with https://github.com/rust-lang/llvm/pull/4 cherry-picked on top.

Awesome job by @neykov for this!
auto merge of #12290 : mrshu/rust/lint-warn-by-default, r=alexcrichton

This first part of my attempts to fix #11432.

In this one I only set NonCamelCaseTypes to warn by default and tried to fix errors that were reported by `make check`.

Please feel free to let me know if I missed something or didn't do it the right way.

Thanks.