Merge bitcoin#29537: lint: Misc improvements for lint runner

742d2b9 lint: Add lint runner build dir and lint pycache to clean task (Fabian Jahr)
cfa057b lint: Add lint runner build dir to gitignore (Fabian Jahr)
fad7f42 lint: Clarify lint runner rust dependency (Fabian Jahr)

Pull request description:

  1. Document the dependency to rust being installed locally
  2. Add the build output directory to gitignore
  3. Clean up the build output directory when running `make clean`

ACKs for top commit:
  maflcko:
    ACK 742d2b9
  TheCharlatan:
    ACK 742d2b9

Tree-SHA512: 36751d852e579830a9e6915b846886a6edaf4e42d508a4773ab502afda10b47c30c7c6bbd3e3158539ea5cf51592c2fe49c4221d271511006653a2d79119ed8c

Author: fanquake

.gitignore

@@ -130,6 +130,7 @@ win32-build
 test/config.ini
 test/cache/*
 test/.mypy_cache/
+test/lint/test_runner/target/
 
 !src/leveldb*/Makefile
 

Makefile.am

@@ -338,7 +338,7 @@ clean-docs:
 clean-local: clean-docs
 	rm -rf coverage_percent.txt test_bitcoin.coverage/ total.coverage/ fuzz.coverage/ test/tmp/ cache/ $(OSX_APP)
 	rm -rf test/functional/__pycache__ test/functional/test_framework/__pycache__ test/cache share/rpcauth/__pycache__
-	rm -rf osx_volname dist/
+	rm -rf osx_volname dist/ test/lint/test_runner/target/ test/lint/__pycache__
 
 test-security-check:
 if TARGET_DARWIN

test/lint/README.md

@@ -16,7 +16,11 @@ result is cached and it prevents issues when the image changes.
 test runner
 ===========
 
-To run all the lint checks in the test runner outside the docker, use:
+To run all the lint checks in the test runner outside the docker you first need
+to install the rust toolchain using your package manager of choice or
+[rustup](https://www.rust-lang.org/tools/install).
+
+Then you can use:
 
 ```sh
 ( cd ./test/lint/test_runner/ && cargo fmt && cargo clippy && RUST_BACKTRACE=1 cargo run )