E.G. for checkout from version control instead.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
$(2)_TARGET_CONFIGURE = $$($(2)_DIR)/.stamp_configured
$(2)_TARGET_PATCH = $$($(2)_DIR)/.stamp_patched
$(2)_TARGET_EXTRACT = $$($(2)_DIR)/.stamp_extracted
-$(2)_TARGET_SOURCE = $$($(2)_DIR)/.stamp_downloaded
+$(2)_TARGET_SOURCE ?= $$($(2)_DIR)/.stamp_downloaded
$(2)_TARGET_UNINSTALL = $$($(2)_DIR)/.stamp_uninstalled
$(2)_TARGET_CLEAN = $$($(2)_DIR)/.stamp_cleaned
$(2)_TARGET_DIRCLEAN = $$($(2)_DIR)/.stamp_dircleaned