Add pre-commit config.

This patch adds `clang-format` as only linter for now. This replaces the
previously used script from `auxil/run-clang-format` which we remove.

This requires the Python program `pre-commit`
(https://pypi.org/project/pre-commit/). With that one can then run
`clang-format` on the whole codebase with

    $ pre-commit run -a clang-format

or on just the staged files

    # Explicitly selecting linter.
    $ pre-commit run clang-format

    # Run all linters (currently just `clang-format`).
    $ pre-commit

`pre-commit` supports managing Git commit hooks so that linters are run
on commit. Linters can be installed with

    $ pre-commit install

The documentation at https://pre-commit.com/ covers these topics in
addition to more information.

.clang-format

@@ -1,10 +1,5 @@
 # Clang-format configuration for Zeek. This configuration requires
 # at least clang-format 12.0.1 to format correctly.
-#
-# The easiest way to run this from the command-line is using the
-# python script in auxil/run-clang-format:
-#
-# python3 auxil/run-clang-format/run-clang-format.py --clang-format-executable /path/to/clang-format -r src -i
 
 Language: Cpp
 Standard: c++17
@@ -102,4 +97,4 @@ IncludeCategories:
   - Regex: '^"zeek/'
     Priority: 4
   - Regex: '.*'
-    Priority: 5
+    Priority: 5

.clang-format-ignore

@@ -1,2 +0,0 @@
-# Ignore everything 3rdparty
-src/3rdparty/*

.gitmodules

@@ -49,6 +49,3 @@
 [submodule "auxil/zeek-client"]
 	path = auxil/zeek-client
 	url = https://github.com/zeek/zeek-client
-[submodule "auxil/run-clang-format"]
-	path = auxil/run-clang-format
-	url = https://github.com/Sarcasm/run-clang-format

.pre-commit-config.yaml

@@ -0,0 +1,8 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+#
+repos:
+- repo: https://github.com/pre-commit/mirrors-clang-format
+  rev: 'v13.0.0'
+  hooks:
+  - id: clang-format

auxil/run-clang-format

@@ -1 +0,0 @@
-Subproject commit 39081c9c42768ab5e8321127a7494ad1647c6a2f

ci/run-clang-format.sh

@@ -1,65 +0,0 @@
-#! /bin/sh
-#
-# Copyright (c) 2020 by the Zeek Project. See LICENSE for details.
-
-base=$(git rev-parse --show-toplevel)
-fix=0
-pre_commit_hook=0
-
-# Directories to run on by default. When changing, adapt .pre-commit-config.yam
-# as well.
-files="src"
-
-error() {
-    test "${pre_commit_hook}" = 0 && echo "$@" >&2 && exit 1
-    exit 0
-}
-
-if [ $# != 0 ]; then
-    case "$1" in
-        --fixit)
-            shift
-            fix=1
-            ;;
-
-        --pre-commit-hook)
-            shift
-            fix=1
-            pre_commit_hook=1
-            ;;
-
-        -*)
-            echo "usage: $(basename $0) [--fixit | --pre-commit-hook] [<files>]"
-            exit 1
-    esac
-fi
-
-test $# != 0 && files="$@"
-
-if [ -z "${CLANG_FORMAT}" ]; then
-    CLANG_FORMAT=$(which clang-format 2>/dev/null)
-fi
-
-if [ -z "${CLANG_FORMAT}" -o ! -x "${CLANG_FORMAT}" ]; then
-    error "Cannot find clang-format. If not in PATH, set CLANG_FORMAT."
-fi
-
-if ! (cd / && ${CLANG_FORMAT} -dump-config | grep -q SpacesInConditionalStatement); then
-    error "${CLANG_FORMAT} does not support SpacesInConditionalStatement. Install custom version and put it into PATH, or point CLANG_FORMAT to it."
-fi
-
-if [ ! -e .clang-format ]; then
-    error "Must execute in top-level directory."
-fi
-
-cmd="${base}/auxil/run-clang-format/run-clang-format.py -r --clang-format-executable ${CLANG_FORMAT} --exclude '*/3rdparty/*' ${files}"
-tmp=/tmp/$(basename $0).$$.tmp
-trap "rm -f ${tmp}" EXIT
-eval "${cmd}" >"${tmp}"
-
-if [ "${fix}" = 1 ]; then
-    test -s "${tmp}" && cat "${tmp}" | git apply -p0
-    true
-else
-    cat "${tmp}"
-fi