update for lib/utils split

Update sources with the new paths

mu/mu-cmd-server.c

@@ -44,7 +44,6 @@
 #endif 	/*PATH_MAX */
 
 #include "mu-runtime.h"
-#include "mu-str.h"
 #include "mu-cmd.h"
 #include "mu-maildir.h"
 #include "mu-query.h"
@@ -53,6 +52,8 @@
 #include "mu-msg-part.h"
 #include "mu-contacts.hh"
 
+#include "utils/mu-str.h"
+
 /* signal handling *****************************************************/
 /*
  * when we receive SIGINT, SIGHUP, SIGTERM, set MU_CAUGHT_SIGNAL to