Add simple top levem Makefile & test list

Makefile

@@ -0,0 +1,13 @@
+DESIGNS := $(file < tests.txt)
+
+.PHONY: ${DESIGNS} all clean
+
+all: ${DESIGNS}
+
+$(DESIGNS):
+	make -C $@ all -j$(nproc)
+
+clean:
+	for dir in $(DESIGNS); do \
+	  make -C $$dir clean;    \
+	done

tests.txt

@@ -0,0 +1,5 @@
+alu \
+counter \
+fifo \
+vai_fifo \
+vai_reg