[glibmm/more-private-exports] class_interface.m4: Export the generated private class

[Chun-wei Fan <fanchunwei src gnome org>]

commit cccced9bbad4615783595876f018f9380966f6e1
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Mon Aug 31 12:52:25 2020 +0800

    class_interface.m4: Export the generated private class
    
    As in the case of class_shared.m4, we need to do the same for
    class_interfacec.m4 as well, in order to export the items in the private
    headers fully.

 tools/m4/class_interface.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tools/m4/class_interface.m4 b/tools/m4/class_interface.m4
index 2ee0aff4..5243b265 100644
--- a/tools/m4/class_interface.m4
+++ b/tools/m4/class_interface.m4
@@ -44,7 +44,7 @@ dnl
 dnl
 dnl
 define(`_PH_CLASS_DECLARATION_INTERFACE',`dnl
-class __CPPNAME__`'_Class : public __CPPPARENT__`'_Class
+class __FUNC_DECORATION__ __CPPNAME__`'_Class : public __CPPPARENT__`'_Class
 {
 public:
   using CppObjectType = __CPPNAME__;