package/systemd: disable audit for host package

Disable audit for host package to avoid getting the following error if
it is found on host:

[84/662] Generating audit_type-list.txt with a meson_exe.py custom command
In file included from <command-line>:32:
./../src/basic/missing_audit.h:7:10: fatal error: libaudit.h: No such file or directory
    7 | #include <libaudit.h>
      |          ^~~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/67782c225c08387c1bbcbea9eee3ca12bc6577cd



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>