Remove ignore-tidy-linelength from tests that no longer need it

[lgrz]

This is a really minor issue. I noticed some tests no longer need the ignore
tidy comment directive.

A quick grep turned up the following files:

src/test/compile-fail/bad-mid-path-type-params.rs
src/test/compile-fail/bad-sized.rs
src/test/compile-fail/coherence-default-trait-impl.rs
src/test/compile-fail/coherence-orphan.rs
src/test/compile-fail/issue-8767.rs
src/test/compile-fail/lint-stability.rs
src/test/compile-fail/lint-uppercase-variables.rs
src/test/compile-fail/typeck-default-trait-impl-outside-crate.rs
src/test/compile-fail/use-after-move-implicity-coerced-object.rs
src/test/debuginfo/gdb-pretty-std.rs

It didn't seem like it was worth opening an issue for this, but if that is not
the case (i.e. it is required), I'll open one up. Thanks!

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see CONTRIBUTING.md for more information.

[alexcrichton]

@bors: r+

Thanks!

[bors]

📌 Commit 2a9e101 has been approved by alexcrichton