More build system adjustments

sandbox/memblock/Makefile

@@ -0,0 +1,2 @@
+include ../sandbox-config.mk
+include ../sandbox-template.mk

sandbox/memblock/main.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main(int argc, const char **argv)
+{
+	printf("Hello, world\n");
+	return 0;
+}