Provide a method of disabling the tests that use dbus

glib's meson scripts search for dbus and, if found, build some additional tests that link with the dbus library. This can fail if dbus is installed but the library is not suitable for some reason. (For example, a user reported to MacPorts that glib failed to build when they were trying to build it universal (i.e. for both i386 and x86_64 architectures) but dbus happened to be installed but was not installed universal.)

To work around this problem, I've added a patch to MacPorts that disables the use of these dbus-based tests, but I would prefer not to have to carry this patch around in MacPorts forever. Would it be possible to add a meson option by which I could indicate my desire to have the dbus-based tests skipped?