[gnome-sdk-images/gnome-3-20] Pass the new --arch option to xdg-app-builder

[Tristan Van Berkom <tvb src gnome org>]

commit dcd11f491039b32b530ad7774926dd7a5a5b3adb
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Mon May 2 13:41:48 2016 -0400

    Pass the new --arch option to xdg-app-builder

 Makefile |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/Makefile b/Makefile
index e0ea005..bde8709 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,9 @@ endef
 all: repo $(patsubst %,%.in,$(SUBST_FILES))
        rm -rf sdk
        $(call subst-metadata)
-       flatpak-builder --force-clean --ccache --require-changes --repo=repo --subject="build of 
org.gnome.Sdk, `date`" ${EXPORT_ARGS} sdk org.gnome.Sdk.json
+       flatpak-builder --force-clean --ccache --require-changes --repo=repo --arch=${ARCH} \
+                        --subject="build of org.gnome.Sdk, `date`" \
+                        ${EXPORT_ARGS} sdk org.gnome.Sdk.json
        rm -rf sdk
 
 repo: