Change the alternative rebar detection to avoid messages

The use of 'make -n' introduced some unwanted messages. This
new solution doesn't have this problem.

core/deps.mk

@@ -62,7 +62,7 @@ define dep_autopatch
 	if [ -f $(DEPS_DIR)/$(1)/Makefile ]; then \
 		if [ 0 != `grep -ci rebar $(DEPS_DIR)/$(1)/Makefile` ]; then \
 			$(call dep_autopatch2,$(1)); \
-		elif [ 0 != `cd $(DEPS_DIR)/$(1)/ && make -n | grep -ci rebar` ]; then \
+		elif [ 0 != `find $(DEPS_DIR)/$(1)/ -type f -name \*.mk -not -name erlang.mk | xargs grep -ci rebar` ]; then \
 			$(call dep_autopatch2,$(1)); \
 		else \
 			$(call dep_autopatch_erlang_mk,$(1)); \