test: rework seccomp testing

Instead of a single test with enabled seccomp, rerun all other
non-destructive and destructive tests for each seccomp level.

test/system/099-scfilter

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features SCFILTER || test_skip "SCFILTER support disabled"
+
+test_start "system call filter in non-destructive tests"
+
+for level in "-1" "1"; do
+	test_message 1 1 "level $level:"
+	for test in 0[0-8][0-9]-*[^_]; do
+		test_message 2 0 "$test"
+		TEST_SCFILTER=$level "./$test" > /dev/null 2> /dev/null
+		result=$?
+
+		if [ $result != 0 ] && [ $result != 9 ] ; then
+			test_bad
+			test_fail
+		fi
+		test_ok
+	done
+done
+
+test_pass