Add dependency injection container for vm

include/vm_di.h

@@ -0,0 +1,21 @@
+#ifndef _VM_DI_H_
+#define _VM_DI_H_
+
+enum vm_di_entry {
+    VM_CPU,
+    VM_MACHINE,
+    VM_REFLECT,
+
+    // This value is the size of the DI container we will construct. As
+    // you can see, it's quite a bit higher than what would be implied
+    // by the number of enum values currently defined--and it is so we
+    // don't have to update this value every time we add a new value.
+    // But be wary that you don't add so many entries as to go beyond
+    // VM_DI_SIZE's defined value!
+    VM_DI_SIZE = 100,
+};
+
+extern void *vm_di_get(int);
+extern int vm_di_set(int, void *);
+
+#endif