meson: Fix build when gnutls is disabled
Requires Meson 0.49 released 4 months ago. If that's too new, I can
change the fix to be slightly-more-ugly. For reference, glib currently
requires 0.48.
Always build tests and only disable running of openssl tests. This gives slightly better coverage when building with only the openssl backend.
Closes #67 (closed)
Edited by Nirbheek Chauhan