QDBusIntrospection: fix position of Annotation definition

When 2e8a48c1cd made
Annotations::mapped_type a struct Annotation instead of just QString,
it inserted the Annotation definition after the first inline user of
Annotations (struct Method).

I don't know why this compiled in the first place, but it did,
probably because of the re-parse-everything-at-closing-of-class rule,
but there's no reason to not move it to before the first users, so do
that.

Found while trying to make QDBusIntrospection a namespace instead of a
struct.

Amends 2e8a48c1cd.

Pick-to: 6.7
Change-Id: I316cb5e49f3476adc5ff5abb023b9d74303ab640
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/dbus/qdbusintrospection_p.h

@@ -67,6 +67,18 @@ public:
                 Q_ATTRIBUTE_FORMAT_PRINTF(3, 4) = 0;
     };
 
+    struct Annotation
+    {
+        SourceLocation location;
+        QString name;
+        QString value;
+
+        inline bool operator==(const Annotation &other) const
+        {
+            return name == other.name && value == other.value;
+        }
+    };
+
     struct Argument
     {
         SourceLocation location;
@@ -116,18 +128,6 @@ public:
                 annotations == other.annotations && type == other.type; }
     };
 
-    struct Annotation
-    {
-        SourceLocation location;
-        QString name;
-        QString value;
-
-        inline bool operator==(const Annotation &other) const
-        {
-            return name == other.name && value == other.value;
-        }
-    };
-
     struct Interface: public QSharedData
     {
         SourceLocation location;