MXS-1354: Fix diagnostic output

The tests failed due to changes in the diagnostic output.

server/core/adminusers.cc

@@ -579,17 +579,25 @@ admin_verify_inet_user(const char *username, const char *password)
  */
 void dcb_PrintAdminUsers(DCB *dcb)
 {
-    dcb_printf(dcb, "Enabled Linux accounts (secure):\n");
+    dcb_printf(dcb, "Enabled Linux accounts (secure)    : ");
 
     if (linux_users)
     {
         users_diagnostic(dcb, linux_users);
     }
+    else
+    {
+        dcb_printf(dcb, "\n");
+    }
 
-    dcb_printf(dcb, "Created network accounts (insecure):\n");
+    dcb_printf(dcb, "Created network accounts (insecure): ");
 
     if (inet_users)
     {
         users_diagnostic(dcb, inet_users);
     }
+    else
+    {
+        dcb_printf(dcb, "\n");
+    }
 }

server/core/users.cc

@@ -88,8 +88,6 @@ public:
     {
         if (m_data.size())
         {
-
-            dcb_printf(dcb, "User names: ");
             const char *sep = "";
 
             for (UserMap::const_iterator it = m_data.begin(); it != m_data.end(); it++)
@@ -99,10 +97,11 @@ public:
             }
             dcb_printf(dcb, "\n");
         }
-        else
-        {
-            dcb_printf(dcb, "Users table is empty\n");
     }
+
+    bool empty() const
+    {
+        return m_data.size() > 0;
     }
 
 private:
@@ -170,8 +169,18 @@ void users_default_diagnostic(DCB* dcb, SERV_LISTENER* port)
 {
     if (port->users)
     {
+        Users* u = reinterpret_cast<Users*>(port->users);
+
+        if (u->empty())
+        {
+            dcb_printf(dcb, "Users table is empty\n");
+        }
+        else
+        {
+            dcb_printf(dcb, "User names: ");
             users_diagnostic(dcb, port->users);
         }
+    }
 }
 
 json_t* users_default_diagnostic_json(const SERV_LISTENER *port)