Fix segfault on linux - catch(...) must not call std::unexpected()

src/libCom/osi/epicsThread.cpp

@@ -73,11 +73,14 @@ extern "C" void epicsThreadCallEntryPoint ( void * pPvt )
             errlogPrintf ( 
                 "epicsThread: Unknown C++ exception in thread \"%s\" at %s\n",
                 name, date );
-            // this should behave as the C++ implementation intends when an 
-            // exception isnt handled. If users dont like this behavior, they 
-            // can install an application specific unexpected handler.
-            std::unexpected ();
+            errlogFlush ();
         }
+        // The Linux NPTL library requires us to re-throw here; it uses
+        // an untyped exception object to shut down threads when we call
+        // pthread_cancel() in the os/posix/osdThread.c myAtExit()
+        // handler, and aborts with "FATAL: exception not rethrown" if
+        // we don't re-throw it.  This solution is incomplete though...
+        throw;
     }
     if ( ! waitRelease ) {
         epicsGuard < epicsMutex > guard ( pThread->mutex );