Bug 1692893 - Minimal patch: Workaround atk extern "C" issue. r=Jamie

They include system headers inside extern "C", which seems wrong and
causes the issue. This is the minimal patch.

Differential Revision: https://phabricator.services.mozilla.com/D105217

other-licenses/atk-1.0/atk/atkobject.h

@@ -20,14 +20,14 @@
 #ifndef __ATK_OBJECT_H__
 #define __ATK_OBJECT_H__
 
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
 #include <glib-object.h>
 #include <atk/atkstate.h>
 #include <atk/atkrelationtype.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
 /*
  * AtkObject represents the minimum information all accessible objects
  * return. This information includes accessible name, accessible