Build SDK repository

When the build is invoked with the fake target "sdk_repo" and
a main target of sdk, win_sdk or sdk_addon, we now create
packages in DIST_DIR that can directly be used to populate the
SDK Repository.
This is quite close to how we actually distribute the SDK.

Change-Id: Ie7e0f789bafd73d5ee2461349155a6e562e2edd9
diff --git a/core/tasks/sdk-addon.mk b/core/tasks/sdk-addon.mk
index 9133312..e21fedc 100644
--- a/core/tasks/sdk-addon.mk
+++ b/core/tasks/sdk-addon.mk
@@ -94,6 +94,10 @@
 .PHONY: sdk_addon
 sdk_addon: $(full_target)
 
+# Keep the name of the addon final zip around for sdk_repo.
+# This is used by development/build/tools/sdk_repo.mk.
+ADDON_SDK_ZIP := $(full_target)
+
 $(call dist-for-goals, sdk_addon, $(full_target))
 
 else # addon_name