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/ancestry.cc
--- src/ancestry.cc.orig
+++ src/ancestry.cc
@@ -8,8 +8,8 @@
 // PURPOSE.
 
 #include "base.hh"
-#include "sanity.hh"
 #include "revision.hh"
+#include "sanity.hh"
 #include "rev_height.hh"
 #include "roster.hh"