ci(compiler): Add script for C++ linting

Add script `.github/workflows/scripts/lint_cpp.sh` that runs
`clang-tidy` with the right parameters to limit checks to source files
not generated automatically.

The script must be run from within the build directory as it relies on
`compiler_commands.json` and `CMakeFiles/CMakeDirectoryInformation.cmake`.

.github/workflows/scripts/lint_cpp.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+die() {
+    echo "$@" >&2
+    exit 1
+}
+
+check_buildfile() {
+    local FILE="$1"
+
+    [ -f "$FILE" ] ||
+	die "$FILE not found. Please run this script from within your build " \
+	    "directory."
+}
+
+check_buildfile "CMakeFiles/CMakeDirectoryInformation.cmake"
+check_buildfile "compile_commands.json"
+
+# Extract toplevel source directory from CMakeDirectoryInformation.cmake
+# containing a line:
+#
+# set(CMAKE_RELATIVE_PATH_TOP_SOURCE "...")
+TOP_SRCDIR=$(grep -o 'set\s*(\s*CMAKE_RELATIVE_PATH_TOP_SOURCE\s\+"[^"]\+")' \
+  CMakeFiles/CMakeDirectoryInformation.cmake | \
+  sed 's/set\s*(\s*CMAKE_RELATIVE_PATH_TOP_SOURCE\s\+"\([^"]\+\)")/\1/g')
+
+[ $? -eq 0 -a ! -z "$TOP_SRCDIR" ] ||
+    die "Could not extract CMAKE_RELATIVE_PATH_TOP_SOURCE from CMake files."
+
+find "$TOP_SRCDIR/"{include,lib,src} \
+     \( -iname "*.h" -o -iname "*.cpp" -o -iname "*.cc" \) | \
+    xargs clang-tidy -p . -header-filter="$TOP_SRCDIR/include/.*\.h"