Fix for issue 447.

Create ebin dir for all apps_dir apps before building any of them.

core/deps.mk

@@ -53,6 +53,9 @@ deps::
 else
 deps:: $(ALL_DEPS_DIRS)
 ifndef IS_APP
+	for dep in $(ALL_APPS_DIRS) ; do \
+		mkdir -p $$dep/ebin; \
+	done
 	$(verbose) for dep in $(ALL_APPS_DIRS) ; do \
 		$(MAKE) -C $$dep IS_APP=1 || exit $$?; \
 	done