Remove unnecessary includes of hashtable.h

And add where necessary.

include/maxscale/listener.h

@@ -19,7 +19,6 @@
 #include <maxscale/cdefs.h>
 #include <maxscale/protocol.h>
 #include <maxscale/ssl.h>
-#include <maxscale/hashtable.h>
 #include <maxscale/jansson.h>
 
 MXS_BEGIN_DECLS

include/maxscale/service.h

@@ -32,7 +32,6 @@
 #include <maxscale/server.h>
 #include <maxscale/listener.h>
 #include <maxscale/filter.h>
-#include <maxscale/hashtable.h>
 #include <maxscale/resultset.h>
 #include <maxscale/config.h>
 #include <maxscale/jansson.h>

include/maxscale/users.h

@@ -17,7 +17,6 @@
  */
 
 #include <maxscale/cdefs.h>
-#include <maxscale/hashtable.h>
 #include <maxscale/dcb.h>
 #include <maxscale/listener.h>
 #include <maxscale/service.h>

server/core/config.cc

@@ -34,6 +34,7 @@
 #include <maxscale/adminusers.h>
 #include <maxscale/alloc.h>
 #include <maxscale/clock.h>
+#include <maxscale/hashtable.h>
 #include <maxscale/housekeeper.h>
 #include <maxscale/http.hh>
 #include <maxscale/json_api.h>

server/modules/filter/cache/cachesimple.hh

@@ -14,7 +14,6 @@
 
 #include <maxscale/cppdefs.hh>
 #include <tr1/unordered_map>
-#include <maxscale/hashtable.h>
 #include "cache.hh"
 #include "cache_storage_api.hh"