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/rcs_import.cc
--- src/rcs_import.cc.orig
+++ src/rcs_import.cc
@@ -16,13 +16,13 @@
 #include <sstream>
 #include <stack>
 #include <stdexcept>
-#include "vector.hh"
 #include <cstring> // memset
 
 #include <boost/shared_ptr.hpp>
 #include <boost/scoped_ptr.hpp>
 #include "lexical_cast.hh"
 #include <boost/tokenizer.hpp>
+#include "vector.hh"
 
 #include "cert.hh"
 #include "constants.hh"