use c++ for some more sources

Do a (superficial) port to c++ of some of the c sources. Update
deps. Fix a few compiler warnings.

mu/mu-cmd-cfind.cc

@@ -27,7 +27,7 @@
 
 #include "mu-cmd.hh"
 #include "mu-contacts.hh"
-#include "mu-runtime.h"
+#include "mu-runtime.hh"
 
 #include "utils/mu-util.h"
 #include "utils/mu-utils.hh"

mu/mu-cmd-find.cc

@@ -32,8 +32,8 @@
 #include "mu-maildir.h"
 #include "mu-query.hh"
 #include "mu-msg-iter.h"
-#include "mu-bookmarks.h"
-#include "mu-runtime.h"
+#include "mu-bookmarks.hh"
+#include "mu-runtime.hh"
 
 #include "utils/mu-util.h"
 #include "utils/mu-str.h"

mu/mu-cmd-index.cc

@@ -33,7 +33,7 @@
 #include "mu-msg.h"
 #include "index/mu-indexer.hh"
 #include "mu-store.hh"
-#include "mu-runtime.h"
+#include "mu-runtime.hh"
 
 #include "utils/mu-util.h"
 

mu/mu-cmd-script.cc

@@ -1,7 +1,5 @@
-/* -*-mode: c; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-*/
-
 /*
-** Copyright (C) 2012-2013 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2012-2020 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
@@ -30,8 +28,8 @@
 #include <errno.h>
 
 #include "mu-cmd.hh"
-#include "mu-script.h"
-#include "mu-runtime.h"
+#include "mu-script.hh"
+#include "mu-runtime.hh"
 
 
 #include "utils/mu-util.h"

mu/mu-cmd-server.cc

@@ -24,7 +24,7 @@
 #include <atomic>
 #include <unistd.h>
 
-#include "mu-runtime.h"
+#include "mu-runtime.hh"
 #include "mu-cmd.hh"
 #include "mu-server.hh"
 

mu/mu-cmd.cc

@@ -34,7 +34,7 @@
 #include "mu-cmd.hh"
 #include "mu-maildir.h"
 #include "mu-contacts.hh"
-#include "mu-runtime.h"
+#include "mu-runtime.hh"
 #include "mu-flags.h"
 
 #include "utils/mu-util.h"

mu/mu.cc

@@ -25,7 +25,7 @@
 
 #include "mu-config.hh"
 #include "mu-cmd.hh"
-#include "mu-runtime.h"
+#include "mu-runtime.hh"
 #include "utils/mu-utils.hh"
 
 using namespace Mu;