Add autopkgtest for test-seccomp

Ship test-seccomp in libsystemd-dev and run it as autopkgtest, so that
it's easier to spot regressions like issue #5215.

Gbp-Dch: Short

debian/rules

@@ -305,8 +305,9 @@ endif
 		(cd debian/$$pkg; find -mindepth 1 -type d) | (cd debian/systemd; xargs rmdir --ignore-fail-on-non-empty --verbose || true); \
 	done
 
-	# ship test-udev, so that we have it for autopkgtests
+	# ship some test programs for autopkgtests
 	install -D build-deb/.libs/test-udev debian/libudev-dev/usr/lib/$(DEB_HOST_MULTIARCH)/udev/test-udev
+	install -D build-deb/.libs/test-seccomp debian/libsystemd-dev/usr/lib/$(DEB_HOST_MULTIARCH)/systemd/test-seccomp
 
 	# Ubuntu specific files
 ifeq ($(DEB_VENDOR),Ubuntu)

debian/tests/control

@@ -82,9 +82,15 @@ Depends: systemd-sysv,
   python3
 Restrictions: needs-root, isolation-machine, needs-recommends, breaks-testbed
 
+Test-Command: /usr/lib/*/systemd/test-seccomp
+Depends: libsystemd-dev
+Restrictions: needs-root, allow-stderr, isolation-container
+Features: test-name=seccomp
+
 Tests: udev
 Depends: tree,
   libudev-dev,
+  libsystemd-dev,
   perl,
   xz-utils,
 Restrictions: needs-root, allow-stderr, isolation-machine
@@ -92,6 +98,7 @@ Restrictions: needs-root, allow-stderr, isolation-machine
 Tests: upstream
 Depends: tree,
   libudev-dev,
+  libsystemd-dev,
   perl,
   xz-utils,
   kbd,
@@ -118,6 +125,7 @@ Depends: systemd-sysv,
   xserver-xorg-video-dummy,
   tree,
   libudev-dev,
+  libsystemd-dev,
   perl,
   xz-utils,
   kbd,