Merge pull request #25 from Legimet/makefile-check-submodules

Check for submodules in makefile

Makefile

@@ -1,3 +1,10 @@
+# Check for submodules
+ifneq ($(words $(wildcard ndless-sdk/thirdparty/nspire-io/Makefile) \
+               $(wildcard ndless-sdk/thirdparty/zlib/configure) \
+               $(wildcard ndless-sdk/thirdparty/freetype2/Makefile)),3)
+        $(error Run `git submodule init' and `git submodule update' to checkout the submodules)
+endif
+
 SUBDIRS = ndless-sdk ndless
 
 all:
@@ -9,4 +16,3 @@ clean:
 	@for i in $(SUBDIRS); do \
 	echo "Clearing in $$i..."; \
 	(cd $$i; make clean) || exit 1; done
-