Move GeanyFunctions declaration back in plugindata.h

This avoids breaking plugins that don't use geanyplugin.h as they
should but include some random headers.

plugins/geanyfunctions.h

@@ -23,9 +23,5 @@
 #ifndef GEANY_FUNCTIONS_H
 #define GEANY_FUNCTIONS_H 1
 
-/* This remains so that older plugins that contain a `GeanyFunctions *geany_functions;`
- * variable in their plugin - as was previously required - will still compile
- * without changes.  */
-typedef struct GeanyFunctionsUndefined GeanyFunctions;
 
 #endif /* GEANY_FUNCTIONS */

src/plugindata.h

@@ -268,6 +268,11 @@ void plugin_cleanup(void);
 /* Deprecated aliases */
 #ifndef GEANY_DISABLE_DEPRECATED
 
+/* This remains so that older plugins that contain a `GeanyFunctions *geany_functions;`
+ * variable in their plugin - as was previously required - will still compile
+ * without changes.  */
+typedef struct GeanyFunctionsUndefined GeanyFunctions;
+
 #define document_reload_file document_reload_force
 
 /** @deprecated - copy into your plugin code if needed.