[gnome-builder] Update POTFILES.skip

[Piotr Drąg <piotrdrag src gnome org>]

commit e5d3c479d422975c566b8579ce5e7749d2c9e14e
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Wed Jun 7 00:22:30 2017 +0200

    Update POTFILES.skip

 po/POTFILES.skip |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/po/POTFILES.skip b/po/POTFILES.skip
index ac23bc6..a69c6fa 100644
--- a/po/POTFILES.skip
+++ b/po/POTFILES.skip
@@ -2,3 +2,4 @@
 # Please keep this file sorted alphabetically.
 data/org.gnome.Builder.desktop.in
 plugins/vala-pack/ide-vala-preferences-addin.c
+subprojects