MFC r326959:

arc lint: ignore /tests/ in chmod

shell scripts in scripts don't need
to be chmod +x to work. In fact most are not.
Of the tests I found from a simple search:
65 are chmod +x
84 are chmod -x

simply disable the check for test shell scripts.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

phabricator related changes:
- don't lint either contrib or crypto: these are both externally written
directories
- add additional linters for spelling (check common typos like teh ->
the)
- chmod linter checks for executible bit on bad files
- merge-conflict checks for merge conflict tokens then may have been
resolved incorrectly
- filename checks for back characters in filenames
- json for json syntax correctness

- remove history.immutable: it is meaningless on subversion, and causes
workflow problems when trying to use git. It it set to 'true' by
default with hg

arc: add linting for python files