tests: Depend on libfile-fcntllock-perl to shut up dpkg-gencontrol

Ubuntu's autopkgtest server always prints

  dpkg-gencontrol: warning: File::FcntlLock not available; using flock which is not NFS-safe

which is somewhat annoying. Work around that by depending on that
perl stuff for the test suite.

Gbp-Dch: ignore

debian/tests/control

@@ -1,3 +1,4 @@
 Tests: run-tests
 Restrictions: allow-stderr
-Depends: @, @builddeps@, fakeroot, wget, stunnel4, lsof, db-util, gnupg, gnupg2
+Depends: @, @builddeps@, fakeroot, wget, stunnel4, lsof, db-util, gnupg, gnupg2,
+         libfile-fcntllock-perl