audit: fixed build by exporting '-D_GNU_SOURCE' via CPPFLAGS in $configprefix for getting O_NOFOLLOW defined

security/audit/audit.conf

@@ -12,6 +12,9 @@
 # GNU General Public License can be found in the file COPYING.
 # --- SDE-COPYRIGHT-NOTE-END ---
 
+# to get O_NOFOLLOW defined
+var_append CPPFLAGS ' ' "-D_GNU_SOURCE"
+
 # prelude support
 if pkginstalled libprelude; then
 	pkgprefix -t libprelude
@@ -27,5 +30,6 @@ if pkginstalled openldap; then
 	var_append LDFLAGS ' ' "-L$root$( pkgprefix libdir openldap )"
 fi
 
+var_insert configprefix ' ' "CPPFLAGS=\"$CPPFLAGS\""
 var_insert configprefix ' ' "CFLAGS=\"$CFLAGS\""
 var_insert configprefix ' ' "LDFLAGS=\"$LDFLAGS\""