util/lint: Unify checks for git worktree

Linters try to determine whether they are running in a git worktree so
that `git grep` can be used instead of `grep`. These checks are done in
different not truly correct ways and thus the linters don't use `git
grep` when running from a worktree subdirectory, e.g. in a git subtree
environment.

Unify checks using `git rev-parse --is-inside-work-tree`.

Change-Id: I3f54afc99ad0f0e3052cffdd32bdd9649cf3d720
Signed-off-by: Alex Thiessen <alex.thiessen.de+coreboot@gmail.com>
Reviewed-on: https://review.coreboot.org/23297
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

0 files changed, 0 insertions, 0 deletions