[gnome-sdk-images] Allow overriding the output ostree repo location

[Alexander Larsson <alexl src gnome org>]

commit 91a5b12252f27f3dde9dbcb650a5ac6c1e4bd7a3
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Thu May 19 14:14:34 2016 +0900

    Allow overriding the output ostree repo location
    
    This allows one to specify the repository with:
    
       make REPO=/path/to/repo
    
    https://bugs.freedesktop.org/show_bug.cgi?id=95483

 Makefile |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/Makefile b/Makefile
index 818982f..9301292 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,6 @@
 # Override the arch with `make ARCH=i386`
 ARCH   ?= $(shell xdg-app --default-arch)
+REPO   ?= repo
 
 # SDK Versions setup here
 #
@@ -23,16 +24,16 @@ define subst-metadata
        @echo "Done.";
 endef
 
-all: repo $(patsubst %,%.in,$(SUBST_FILES))
+all: ${REPO} $(patsubst %,%.in,$(SUBST_FILES))
        rm -rf sdk
        $(call subst-metadata)
-       flatpak-builder --force-clean --ccache --require-changes --repo=repo --arch=${ARCH} \
+       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:
-       ostree  init --mode=archive-z2 --repo=repo
+${REPO}:
+       ostree  init --mode=archive-z2 --repo=${REPO}
 
 check:
        json-glib-validate org.gnome.Sdk.json