include: do not override kernel headers with libaudit headers

Overriding <linux/audit.h> to implicitly include <libaudit.h> turns out to
be problematic. Because <linux/audit.h> is pulled in by various other kernel
headers, any source file including those kernel headers indirectly ends up
depending on <libaudit.h>, even if the executable or library being built
does not require libaudit at all.

Let's drop the override header and include <libaudit.h> only where explicitly
needed. This also moves the fallback definitions of AUDIT_SERVICE_* and
MAX_AUDIT_MESSAGE_LENGTH to libaudit-util.h.

src/include/meson.build

@@ -33,11 +33,6 @@ ipproto_sources = files(
         'uapi/linux/in.h',
 )
 
-# Source files that provides AUDIT_XYZ
-audit_sources = files(
-        'override/linux/audit.h',
-)
-
 # Source files that provides KEY_XYZ
 keyboard_sources = files(
         'uapi/linux/input.h',

src/include/override/linux/audit.h

@@ -1,33 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-#pragma once
-
-#include_next <linux/audit.h>   /* IWYU pragma: export */
-
-#if HAVE_AUDIT
-#  include <libaudit.h>         /* IWYU pragma: export */
-#endif
-
-#include <assert.h>
-
-/* We use static_assert() directly here instead of assert_cc()
- * because if we include macro.h in this header, the invocation
- * of generate-audit_type-list.sh becomes more complex.
- */
-
-#ifndef AUDIT_SERVICE_START
-#  define AUDIT_SERVICE_START 1130 /* Service (daemon) start */
-#else
-static_assert(AUDIT_SERVICE_START == 1130, "");
-#endif
-
-#ifndef AUDIT_SERVICE_STOP
-#  define AUDIT_SERVICE_STOP 1131 /* Service (daemon) stop */
-#else
-static_assert(AUDIT_SERVICE_STOP == 1131, "");
-#endif
-
-#ifndef MAX_AUDIT_MESSAGE_LENGTH
-#  define MAX_AUDIT_MESSAGE_LENGTH 8970
-#else
-static_assert(MAX_AUDIT_MESSAGE_LENGTH == 8970, "");
-#endif