Add 'examples' top level Makefile for building all examples together

examples/Makefile

@@ -0,0 +1,29 @@
+warning:
+	@echo "******************************************************"
+	@echo "You may not want this Makefile, even though it's here!"
+	@echo "******************************************************"
+	@echo ""
+	@echo "SUGGESTIONS:"
+	@echo "Running 'make' in one of the subdirectories will build a single example."
+	@echo "Running 'make help' in one of the subdirectories will print some help."
+	@echo ""
+	@echo "OTHERWISE:"
+	@echo "This makefile is for building all of the examples at once, as a developer test."
+	@echo "To use it, run 'make build-examples' or 'make rebuild-examples'"
+	@echo
+
+build-examples:
+	set -e
+	for example in `find . -mindepth 2 -name Makefile | sed s/Makefile//)`; do
+	   $(MAKE) -C $$example
+	done
+
+rebuild-examples:
+	set -e
+	for example in `find . -mindepth 2 -name Makefile | sed s/Makefile//)`; do
+	   $(MAKE) -C $$example rebuild
+	done
+
+.PHONY: warning rebuild-examples build-examples
+.NOTPARALLEL:
+.ONESHELL: