[evince] backend-pdf: make function static as only used in this file

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

commit acba550d17425d9675d96d65e411b278b5b264b4
Author: vanadiae <vanadiae35 gmail com>
Date:   Wed Jun 10 17:37:37 2020 +0200

    backend-pdf: make function static as only used in this file

 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 4b36165b..d5845e44 100644
--- a/backend/pdf/ev-poppler.cc
+++ b/backend/pdf/ev-poppler.cc
@@ -1962,7 +1962,7 @@ pdf_document_images_get_image_mapping (EvDocumentImages *document_images,
        return ev_mapping_list_new (page->index, g_list_reverse (retval), (GDestroyNotify)g_object_unref);
 }
 
-GdkPixbuf *
+static GdkPixbuf *
 pdf_document_images_get_image (EvDocumentImages *document_images,
                               EvImage          *image)
 {