build: don't use Boost multi_index serialization

We don't use the serialilzation or archiving facilities of multi_index.
So globally disable support, which gives a minor improvement in build
time, i.e less preprocessing work.

See: https://www.boost.org/doc/libs/1_78_0/libs/multi_index/doc/tutorial/creation.html

configure.ac

@@ -1435,6 +1435,9 @@ if test "$use_boost" = "yes"; then
     AC_MSG_ERROR([only libbitcoinconsensus can be built without Boost])
   fi
 
+  dnl we don't use multi_index serialization
+  BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_MULTI_INDEX_DISABLE_SERIALIZATION"
+
   if test "$suppress_external_warnings" != "no"; then
     BOOST_CPPFLAGS=SUPPRESS_WARNINGS($BOOST_CPPFLAGS)
   fi