libtest: rename `BenchHarness` to `Bencher`
Closes #12640
Add more type signatures to the docs; tweak a few of them.

Someone reading the docs won't know what the types of various things
are, so this adds them in a few meaningful places to help with
comprehension.

cc #13423.
auto merge of #13236 : liigo/rust/rename-benchharness, r=huonw

Closes #12640

based on PR #13030, rebased, and passed all tests.
auto merge of #13458 : huonw/rust/doc-signatures, r=alexcrichton

Add more type signatures to the docs; tweak a few of them.

Someone reading the docs won't know what the types of various things
are, so this adds them in a few meaningful places to help with
comprehension.

cc #13423.
Parameterize contains_nul for BytesContainer.
Simplify GenericPath::set_extension.
auto merge of #13395 : Ryman/rust/bytecontainer_impl_container, r=alexcrichton

Also some minor cleanup in Path related to this.
Append missing padding after last field of struct

This patch fixes issue #13186.

When generating constant expression for enum, it is possible that
alignment of expression may be not equal to alignment of type.  In that
case space after last struct field must be padded to match size of value
and size of struct. This commit adds that padding.

See detailed explanation in src/test/run-pass/trans-tag-static-padding.rs