build: Make dependency package archive timestamps deterministic

Author: hebasto

depends/funcs.mk

@@ -233,7 +233,9 @@ $($(1)_postprocessed): | $($(1)_staged)
 	touch $$@
 $($(1)_cached): | $($(1)_dependencies) $($(1)_postprocessed)
 	echo Caching $(1)...
-	cd $$($(1)_staging_dir)/$(host_prefix); find . | sort | $(build_TAR) --no-recursion -czf $$($(1)_staging_dir)/$$(@F) -T -
+	cd $$($(1)_staging_dir)/$(host_prefix); \
+	  find . ! -name '.stamp_postprocessed' -print0 | TZ=UTC xargs -0r touch -h -m -t 200001011200; \
+	  find . ! -name '.stamp_postprocessed' | LC_ALL=C sort | $(build_TAR) --numeric-owner --no-recursion -czf $$($(1)_staging_dir)/$$(@F) -T -
 	mkdir -p $$(@D)
 	rm -rf $$(@D) && mkdir -p $$(@D)
 	mv $$($(1)_staging_dir)/$$(@F) $$(@)