tests: Run test requiring the network only in maintainer-mode.
* dirmngr/Makefile.am (noinst_PROGRAMS, TESTS): Add module_net_tests. (module_tests): Move t-dns-test to ... (module_net_tests): here.
- Debian-bug-id: #836259
- Signed-off-by: Werner Koch <wk@gnupg.org>