CI: add a script and job to run cmakelint

A number of checks don't match our style or are buggy and so are disabled.

Co-authored-by: Viktor Szakats <vszakats@users.noreply.github.com>
Fixes #14580
Closes #14665

scripts/Makefile.am

@@ -24,7 +24,7 @@
 
 EXTRA_DIST = coverage.sh completion.pl firefox-db2pem.sh checksrc.pl    \
  mk-ca-bundle.pl schemetable.c cd2nroff nroff2cd cdall cd2cd managen \
- dmaketgz release-tools.sh verify-release
+ dmaketgz release-tools.sh verify-release cmakelint.sh
 
 ZSH_FUNCTIONS_DIR = @ZSH_FUNCTIONS_DIR@
 FISH_FUNCTIONS_DIR = @FISH_FUNCTIONS_DIR@

scripts/cmakelint.sh

@@ -0,0 +1,50 @@
+#!/bin/sh
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) Dan Fandrich, <dan@coneharvesters.com>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+# SPDX-License-Identifier: curl
+#
+###########################################################################
+
+# Run cmakelint on the curl source code. It will check all files given on the
+# command-line, or else all relevant files in git, or if not in a git
+# repository, all files starting in the tree rooted in the current directory.
+#
+# cmakelint can be installed from PyPi with the command "python3 -m pip install
+# cmakelint".
+#
+# The xargs invocation is portable, but does not preserve spaces in file names.
+# If such a file is ever added, then this can be portably fixed by switching to
+# "xargs -I{}" and appending {} to the end of the xargs arguments (which will
+# call cmakelint once per file) or by using the GNU extension "xargs -d'\n'".
+{
+  if [ -n "$1" ]; then
+    for A in "$@"; do printf "%s\n" "$A"; done
+  elif git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+    git ls-files
+  else
+    # strip off the leading ./ to make the grep regexes work properly
+    find . -type f | sed 's@^\./@@'
+  fi
+} | grep -E '(/CMake|\.cmake$)' | grep -v -E '(\.h\.cmake|\.in)$' \
+  | xargs \
+  cmakelint \
+    --spaces=2 --linelength=132 \
+    --filter=-whitespace/indent,-convention/filename,-package/stdargs