tests: move to subdir, move to meson

De-clutter the source directories a bit. Ensure tests build with meson, and
remove from autotools in a few places (no need to do things twice).

mu/tests/meson.build

@@ -0,0 +1,41 @@
+## Copyright (C) 2021 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software Foundation,
+## Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+#
+# tests
+#
+test('test_cmd',
+     executable('test-cmd',
+		'test-mu-cmd.cc',
+		install: false,
+		dependencies: [glib_dep, lib_test_mu_common_dep, config_h_dep, lib_mu_dep]))
+test('test_cmd_cfind',
+     executable('test-cmd-cfind',
+		'test-mu-cmd-cfind.cc',
+		install: false,
+		dependencies: [glib_dep, lib_test_mu_common_dep, config_h_dep, lib_mu_dep]))
+test('test_cmd_query',
+     executable('test-cmd-query',
+		'test-mu-query.cc',
+		install: false,
+		dependencies: [glib_dep, lib_test_mu_common_dep, config_h_dep, lib_mu_dep]))
+
+gmime_test = executable(
+  'gmime-test', [
+  'gmime-test.c'
+],
+  dependencies: [ glib_dep, gmime_dep ],
+  install: false)