Context::getSecurityPlugins() no return of non-const ref.

Return of map as non-const ref. allows callers to modify.
Probably unintended.

src/remoteClient/clientContextImpl.cpp

@@ -4472,7 +4472,7 @@ private:
         }
     }
 
-    std::map<std::string, std::tr1::shared_ptr<SecurityPlugin> >& getSecurityPlugins() OVERRIDE FINAL
+    const securityPlugins_t& getSecurityPlugins() OVERRIDE FINAL
     {
         return SecurityPluginRegistry::instance().getClientSecurityPlugins();
     }