Auto-generate RNA-structs declarations in RNA_prototypes.h

So far it was needed to declare a new RNA struct to `RNA_access.h` manually.
Since 9b298cf3db we generate a `RNA_prototypes.h` for RNA property
declarations. Now this also includes the RNA struct declarations, so they don't
have to be added manually anymore.

Differential Revision: https://developer.blender.org/D13862

Reviewed by: brecht, campbellbarton

source/blender/python/intern/bpy_driver.c

@@ -24,6 +24,7 @@
 #include "BKE_global.h"
 
 #include "RNA_access.h"
+#include "RNA_prototypes.h"
 #include "RNA_types.h"
 
 #include "bpy_rna_driver.h" /* for pyrna_driver_get_variable_value */