Move slice::exact_chunks directly above exact_chunks_mut for more con…

…sistent docs order

See https://github.com/rust-lang/rust/issues/47115#issuecomment-392532855

See https://github.com/rust-lang/rust/issues/47115#issuecomment-392532855

Rollup of 6 pull requests

Successful merges:

 - #51288 (Remove rustdoc-specific is_import field from HIR)
 - #51299 (const fn integer operations)
 - #51317 (Allow enabling incremental via config.toml)
 - #51323 (Generate br for all two target SwitchInts)
 - #51326 (Various minor slice iterator cleanups)
 - #51329 (Remove the unused `-Z trans-time-graph` flag.)

Failed merges:

Remove the unused `-Z trans-time-graph` flag.

Rebase of #50783 has accidentally revived the flag (which should be renamed to `-Z codegen-time-graph` by #50615).

Various minor slice iterator cleanups

See individual commits

Generate br for all two target SwitchInts

Instead of only for booleans. This means that `if let` also becomes a br.

Apart from making the IR slightly simpler, this is supported by FastISel (#4353).

Allow enabling incremental via config.toml

r? @QuietMisdreavus

const fn integer operations

A follow up to #51171
Fixes #51267

Makes a lot of the integer methods (`swap_bytes`, `count_ones` etc) `const fn`s. See #51267 for a discussion about why this is wanted and the solution used.

Remove rustdoc-specific is_import field from HIR

Fixes #47100.

I believe that there is no need to check for the name being the same, as this
part of rustdoc seems to be strictly interested in exploring "public modules."
Re-exports from the same module cannot visit another module; and, re-exports
cannot export items with a greater visibility than that item declares.
Therefore, I think this code is either sufficient, or in fact does more than
is necessary, depending on whether rustdoc cares about the re-export itself.

r? @EddyB

Point to the rustdoc attribute where intralink resolution failed.

implement #[panic_implementation]

This implements the `#[panic_implementation]` attribute as instructed in https://github.com/rust-lang/rust/issues/44489#issuecomment-381324623

I haven't run the full test suite yet but at least all the compile-fail tests pass.

r? @nagisa

Clean up dependency tracking in Rustbuild [1/2]

Initial refactor of the `Mode` enum. Still a WIP
Ref  #50509

r? @Mark-Simulacrum

Rebase of #50783 has accidentally revived the flag (which should be
renamed to `-Z codegen-time-graph` by #50615).

make is_tool inherent prop of mode

fix errors from rebase

resolve issues from review

These don't exist anymore.

update the miri submodule

the submodule currently seems to be pointing to a miri branch that has been deleted.

r? @TimNN

not required because this is a Rust function

Rollup of 6 pull requests

Successful merges:

 - #51143 (Specify that packed types must derive, not implement, Copy)
 - #51226 (Make Layout's align a NonZeroUsize)
 - #51297 (Fix run button style)
 - #51306 (impl Default for &mut str)
 - #51312 (Clarify the difference between get_mut and into_mut for OccupiedEntry)
 - #51313 (use type name in E0599 enum variant suggestion)

Failed merges: