Set the _owner even in the release builds.

We are warning about thread affinity even in the non-debug builds.

Change-Id: Ia91170765e9f4a29939dee847899345e9396d2c3

wsd/AdminModel.hpp

@@ -208,7 +208,7 @@ private:
     std::list<unsigned> _cpuStats;
     unsigned _cpuStatsSize = 100;
 
-    // always enabled to avoid ABI change in debug mode ...
+    /// We check the owner even in the release builds, needs to be always correct.
     std::thread::id _owner;
 };