[gimp] Issue #4532: tests fail due to app/gimp-update.c not in POTFILES.

[Jehan <jehanp src gnome org>]

commit eca8076be615c560679a1d3b577a0b136e7a5620
Author: Jehan <jehan girinstud io>
Date:   Sun Jan 26 11:34:54 2020 +0100

    Issue #4532: tests fail due to app/gimp-update.c not in POTFILES.

 po/POTFILES.in | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 33dfd07a7e..f3a5e5c906 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -9,6 +9,7 @@ desktop/gimp.desktop.in.in
 
 app/about.h
 app/app.c
+app/gimp-update.c
 app/gimp-version.c
 app/main.c
 app/sanity.c