test: Make lint-includes.sh work from any directory #16768

Before this change it works from root folder of bitcoin git repo, but if you do cd test/lint; ./test-includes.sh, you will have a lot of false positive messages like this:

Good job! The circular dependency "chainparamsbase -> util/system -> chainparamsbase" is no longer present.
Please remove it from EXPECTED_CIRCULAR_DEPENDENCIES in ./lint-circular-dependencies.sh
to make sure this circular dependency is not accidentally reintroduced.

Good job! The circular dependency "index/txindex -> validation -> index/txindex" is no longer present.
Please remove it from EXPECTED_CIRCULAR_DEPENDENCIES in ./lint-circular-dependencies.sh
to make sure this circular dependency is not accidentally reintroduced.

Changed push/popd to cd, Travis CI didn't like it.

In test/lint/lint-includes.sh line 15:
pushd "$(dirname $0)/../.." > /dev/null
^-- SC2164: Use 'cd ... || exit' or 'cd ... || return' in case cd fails.
In test/lint/lint-includes.sh line 114:
popd > /dev/null
^--------------^ SC2164: Use 'cd ... || exit' or 'cd ... || return' in case cd fails.

Rebooted the test to be sure, and Travis still doesn't like it:

In test/lint/lint-includes.sh line 15:
cd "$(dirname $0)/../.." > /dev/null
^-- SC2164: Use 'cd ... || exit' or 'cd ... || return' in case cd fails.
In test/lint/lint-includes.sh line 114:
cd - > /dev/null
^--------------^ SC2164: Use 'cd ... || exit' or 'cd ... || return' in case cd fails.
^--------------^ SC2103: Use a ( subshell ) to avoid having to cd back.
For more information:
  https://www.shellcheck.net/wiki/SC2164 -- Use 'cd ... || exit' or 'cd ... |...
  https://www.shellcheck.net/wiki/SC2103 -- Use a ( subshell ) to avoid havin...
^---- failure generated from test/lint/lint-shell.sh

It wants the check of exist status of cd, should be fine now.

Tested ACK 01825553fd1e10d95c8b1539b8d0245ede39fd74

Nice developer ergonomics fix! @kristapsk, you might want to apply this fix to the other git based linters as well to allow for running them from any directory. Perhaps in a follow-up PR? :-)

These linters invoke git:

$ git grep -lE "[^a-z]git[^a-z]" -- test/lint/ ":(exclude)*.md"
test/lint/check-doc.py
test/lint/commit-script-check.sh
test/lint/extended-lint-cppcheck.sh
test/lint/git-subtree-check.sh
test/lint/lint-assertions.sh
test/lint/lint-filenames.sh
test/lint/lint-format-strings.sh
test/lint/lint-include-guards.sh
test/lint/lint-includes.sh
test/lint/lint-locale-dependence.sh
test/lint/lint-logs.sh
test/lint/lint-python-dead-code.sh
test/lint/lint-python-mutable-default-parameters.sh
test/lint/lint-python-utf8-encoding.sh
test/lint/lint-python.sh
test/lint/lint-qt.sh
test/lint/lint-rpc-help.sh
test/lint/lint-shebang.sh
test/lint/lint-shell-locale.sh
test/lint/lint-shell.sh
test/lint/lint-spelling.sh
test/lint/lint-tests.sh
test/lint/lint-whitespace.sh

I'd rather not change all the linter scripts to provide maximum flexibility. This is all code that needs to be reviewed and maintained. And changing one script to be flexible, but keeping the others doesn't really help.

So -0 from me.

So, as I understand, @MarcoFalke is against merging this, but @practicalswift things it's good idea to modify other scripts too. What do others think? I will not stand and fight for this too hard, does not seem to be of high importance, just think it's not good that script gives false positive outputs just because it's ran from the wrong directory.

@kristapsk @MarcoFalke Even if the other scripts are left unchanged I think this specific change is worth doing: lint-includes.sh gives very misleading output if not run from the repo root.

Ok, fair enough

ACK 9d518b5f0ffedc79b98dba7aed35637d11e7f736, tested.