lib: centralize xapian include, enable move semantics

Only include xapian.h in one place, so we can have consistent options.
With that in place, we can enable C++ move semantics.

We don't do anything with that yet, but we check in the meson.build file
to see if we have the required xapian version.

lib/message/mu-document.hh

@@ -19,7 +19,6 @@
 #ifndef MU_DOCUMENT_HH__
 #define MU_DOCUMENT_HH__
 
-#include <xapian.h>
 #include <utility>
 #include <string>
 #include <vector>

lib/message/mu-fields.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -24,7 +24,7 @@
 #include <string_view>
 #include <algorithm>
 #include <array>
-#include <xapian.h>
+#include <mu-xapian-db.hh>
 #include <utils/mu-utils.hh>
 #include <utils/mu-option.hh>
 

lib/message/mu-message.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -25,6 +25,8 @@
 #include <vector>
 #include <iostream>
 
+#include "mu-xapian-db.hh"
+
 #include "mu-contact.hh"
 #include "mu-priority.hh"
 #include "mu-flags.hh"
@@ -33,8 +35,6 @@
 #include "mu-message-part.hh"
 #include "mu-message-file.hh"
 
-#include <xapian.h>
-
 #include "utils/mu-utils.hh"
 #include "utils/mu-option.hh"
 #include "utils/mu-result.hh"