[evince] backend-pdf: use SaveToBufferData only with "struct" before

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 459c91d44cf23336db7d2945c1c882cad8b90c76
Author: vanadiae <vanadiae35 gmail com>
Date:   Wed Jun 10 17:30:40 2020 +0200

    backend-pdf: use SaveToBufferData only with "struct" before
    
    As struct SaveToBufferData doesn't have any typedef to be able
    to use it without "struct". This won't compile in C without
    "struct" before.

 backend/pdf/ev-poppler.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/backend/pdf/ev-poppler.cc b/backend/pdf/ev-poppler.cc
index 4b0f7b60..4b36165b 100644
--- a/backend/pdf/ev-poppler.cc
+++ b/backend/pdf/ev-poppler.cc
@@ -4282,7 +4282,7 @@ attachment_save_to_buffer_callback (const gchar  *buf,
                                    gpointer      user_data,
                                    GError      **error)
 {
-       struct SaveToBufferData *sdata = (SaveToBufferData *)user_data;
+       struct SaveToBufferData *sdata = (struct SaveToBufferData *)user_data;
        gchar *new_buffer;
        gsize new_max;