rust: move rustfmt.toml to repo root so it can be used by `hg fix`
`hg fix` runs the formatters from the repo root so it doesn't pick up
the `rustfmt.toml` configs we had in each the `hg-core`, `hg-cpython`,
and `rhg` packages, which resulted in warnings about `async fn` not
existing in Rust 2015. This patch moves the `rustfmt.toml` file to the
root so `hg fix` will use it.
By putting the `rustfmt.toml` file in a higher-level directory, it
also applies to the `chg` and `hgcli` packages. That makes
`test-check-rust-format.t` fail, so this patch also applies the new
formatting rules to those packages.
Differential Revision: https://phab.mercurial-scm.org/D9142
$ hg init t
$ cd t
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg add b
$ hg commit -m "commit #2"
created new head
$ cd ..; rm -r t
$ mkdir t
$ cd t
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg commit -A -m "commit #2"
adding b
created new head
$ cd ..; rm -r t
$ hg init t
$ cd t
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg remove b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg commit -A -m "commit #2"
adding b
created new head
$ hg merge 'wdir()'
abort: merging with the working copy has no effect
[255]
$ cd ..