[Steam only] Fix validation issues

We won't ever compile this code with DBGFLAG_VALIDATE so it doesn't matter here.

P4:6571406

Author: zpostfacto

src/steamnetworkingsockets/steamnetworkingsockets_thinker.cpp

@@ -246,8 +246,13 @@ void IThinker::Thinker_ProcessThinkers()
 #ifdef DBGFLAG_VALIDATE
 void Thinker_ValidateStatics( CValidator &validator )
 {
-	ValidateObj( s_queueThinkers );
+	ValidateRecursive( s_queueThinkers );
 }
+
+void IThinker::Validate( CValidator &validator, const char *pchName )
+{
+}
+
 #endif
 
 } // namespace SteamNetworkingSocketsLib

src/steamnetworkingsockets/steamnetworkingsockets_thinker.h

@@ -76,6 +76,10 @@ class IThinker
 
 	void InternalSetNextThinkTime( SteamNetworkingMicroseconds usecTargetThinkTime );
 	void InternalEnsureMinThinkTime( SteamNetworkingMicroseconds usecTargetThinkTime );
+public:
+	#ifdef DBGFLAG_VALIDATE
+	virtual void Validate( CValidator &validator, const char *pchName );
+	#endif
 };
 template <typename L>
 class ILockableThinker : public IThinker