backend/native: Export output, crtc and monitor manager types

They will be derived from the test backend, which lives in its own
library.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3812>

src/backends/native/meta-crtc-native.h

@@ -20,6 +20,7 @@
 #include "backends/meta-crtc.h"
 
 #define META_TYPE_CRTC_NATIVE (meta_crtc_native_get_type ())
+META_EXPORT_TEST
 G_DECLARE_DERIVABLE_TYPE (MetaCrtcNative, meta_crtc_native,
                           META, CRTC_NATIVE,
                           MetaCrtc)

src/backends/native/meta-monitor-manager-native.h

@@ -32,6 +32,7 @@
 typedef struct _MetaGpuKms MetaGpuKms;
 
 #define META_TYPE_MONITOR_MANAGER_NATIVE (meta_monitor_manager_native_get_type ())
+META_EXPORT_TEST
 G_DECLARE_DERIVABLE_TYPE (MetaMonitorManagerNative, meta_monitor_manager_native,
                           META, MONITOR_MANAGER_NATIVE,
                           MetaMonitorManager)

src/backends/native/meta-output-native.h

@@ -20,6 +20,7 @@
 #include "backends/meta-output.h"
 
 #define META_TYPE_OUTPUT_NATIVE (meta_output_native_get_type ())
+META_EXPORT_TEST
 G_DECLARE_DERIVABLE_TYPE (MetaOutputNative, meta_output_native,
                           META, OUTPUT_NATIVE,
                           MetaOutput)