also compile the programs in the util directory by default, not only

do we want to test they can be compiled, but also samples may use/require
them. we might want to install them too, perhaps

util/Makefile

@@ -0,0 +1,20 @@
+
+.PHONY: atari gamate zlib
+
+all: atari gamate zlib
+
+atari:
+	@$(MAKE) -C atari --no-print-directory $@
+gamate:
+	@$(MAKE) -C gamate --no-print-directory $@
+zlib:
+	@$(MAKE) -C zlib --no-print-directory $@
+
+mostlyclean clean:
+	@$(MAKE) -C atari --no-print-directory $@
+	@$(MAKE) -C gamate --no-print-directory $@
+	@$(MAKE) -C zlib --no-print-directory $@
+
+install zip:
+
+