tidy should skip RLS files

[spastorino]

tidy should skip RLS files or even more, it should probably skip untracked files.

[santiago@galago rust1 (make-place-builder)]$ ./x.py test -i --stage 1 --keep-stage 1 src/tools/tidy
Updating only changed submodules
Submodules updated in 0.02 seconds
    Finished dev [unoptimized] target(s) in 0.12s
Building stage0 tool tidy (x86_64-unknown-linux-gnu)
    Finished release [optimized + debuginfo] target(s) in 0.12s
tidy check
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/backtrace-supported.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/backtrace-supported.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/config.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/config.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/backtrace-supported.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/backtrace-supported.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/config.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc_mir/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/config.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/backtrace-supported.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/backtrace-supported.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/config.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-f1076cfdc06a1d7a/out/config.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/backtrace-supported.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/backtrace-supported.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/config.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-3648bfa24214c6f1/out/config.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-803a19e316a7f5c0/out/backtrace-supported.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-803a19e316a7f5c0/out/backtrace-supported.h: leading newline
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-803a19e316a7f5c0/out/config.h: empty file
tidy error: /home/santiago/src/oss/rust1/src/librustc/target/rls/debug/build/backtrace-sys-803a19e316a7f5c0/out/config.h: leading newline
some tidy checks failed

[euclio]

This is a regression; it was originally reported at #52158 and fixed in #55213.

[Mark-Simulacrum]

Hm so to be clear it is currently broken but was previously already fixed?

We probably just need to re-add target to the filter_dirs list here.

[spastorino]

This was changed in this commit by @petrochenkov. I guess there may be good reasons to remove all these directories, I'd say that we need to skip things that are listed on .gitignore :).

[petrochenkov]

I assumed target was only created next to the top level Cargo.toml so it could not be visited by tidy anyway.
If that's not the case, please feel free to re-add it (with a comment, if possible).