Build fixes.

node/Buf.hpp

@@ -147,7 +147,7 @@ public:
 	{
 		Buf::Slice r;
 
-		typename FCV<Buf::Slice,FCVC>::const_iterator s(fcv.begin());
+		typename FCV<Buf::Slice,FCVC>::iterator s(fcv.begin());
 		unsigned int l = s->e - s->s;
 		if (l <= ZT_BUF_MEM_SIZE) {
 			r.b.move(s->b);

node/Defragmenter.hpp

@@ -260,7 +260,7 @@ public:
 			// Slices are TriviallyCopyable and so may be memcpy'd from e->message to
 			// the result parameter. This is fast.
 			e->message.unsafeMoveTo(message);
-			e->message.lastUsed = -1; // mark as "done" and force GC to collect
+			e->lastUsed = -1; // mark as "done" and force GC to collect
 
 			return COMPLETE;
 		}