[druntime: Little mergefix for core.thread.fiber.base]

Author: kinke

runtime/druntime/src/core/thread/fiber/base.d

@@ -682,6 +682,11 @@ private:
 
         // Set first time switchIn called to indicate this Fiber's Thread
         ThreadBase m_curThread;
+
+        version (SjLj_Exceptions)
+        {
+            SjLjFuncContext* m_sjljExStackTop;
+        }
     }
     Throwable           m_unhandled;
     State               m_state;