+# Defer all targets up to the upper-level
+#
+# This requires two recipes. The first to cover the case of no
+# explicit target specifed (so when invoked as "make" we call "make"
+# at the upper-level) and then a .DEFAULT recipe to pass any explicit
+# target up as well, (so that an invocation of "make foo" results in a
+# call to "make foo" above.
+all:
+ $(MAKE) -C ..
+
+.DEFAULT:
+ $(MAKE) -C .. $@