A function macro named E clashes with internal boost definitions.  Rearrange
the order of header inclusion so that affected boost headers are included
before monotone defines the macro.

Also, stop bundling boost/circular_buffer, which is available in current
versions of boost. From Fedora.

Index: src/xdelta.cc
--- src/xdelta.cc.orig
+++ src/xdelta.cc
@@ -26,7 +26,6 @@
 
 #include "base.hh"
 #include <algorithm>
-#include "vector.hh"
 #include <set>
 #include <sstream>
 #include <cstring>  // memcmp
@@ -34,6 +33,7 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/version.hpp>
 
+#include "vector.hh"
 #include "adler32.hh"
 #include "hash_map.hh"
 #include "numeric_vocab.hh"