chardev: express dependency on io/

chardev is using qio functions, so express that in the Meson internal
dependency.  (I found this when adding character devices bindings for
Rust; they initially needed the io dependency added by hand).

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -4015,7 +4015,7 @@ libchardev = static_library('chardev', chardev_ss.sources() + genh,
                             build_by_default: false)
 
 chardev = declare_dependency(objects: libchardev.extract_all_objects(recursive: false),
-                             dependencies: chardev_ss.dependencies())
+                             dependencies: [chardev_ss.dependencies(), io])
 
 hwcore_ss = hwcore_ss.apply({})
 libhwcore = static_library('hwcore', sources: hwcore_ss.sources() + genh,