use SIGALRM instead of SIGURG to wakeup blocking socket calls

src/ca/tcpiiu.cpp

@@ -702,7 +702,7 @@ void tcpiiu::initiateAbortShutdown ( epicsGuard < callbackMutex > & cbGuard, //
                 }
             }
             break;
-        case esscimqi_socketSigurgRequired:
+        case esscimqi_socketSigAlarmRequired:
             this->recvThread.interruptSocketRecv ();
             this->sendThread.interruptSocketSend ();
             break;

src/libCom/osi/os/posix/systemCallIntMech.cpp

@@ -18,5 +18,5 @@
 enum epicsSocketSystemCallInterruptMechanismQueryInfo 
         epicsSocketSystemCallInterruptMechanismQuery ()
 {
-    return esscimqi_socketSigurgRequired;
+    return esscimqi_socketSigAlarmRequired;
 }

src/libCom/osi/osiSock.h

@@ -176,7 +176,7 @@ epicsShareFunc osiSockAddr epicsShareAPI osiLocalAddr (SOCKET socket);
 enum epicsSocketSystemCallInterruptMechanismQueryInfo { 
     esscimqi_socketCloseRequired, 
     esscimqi_socketBothShutdownRequired,
-    esscimqi_socketSigurgRequired,
+    esscimqi_socketSigAlarmRequired,
     esscimqi_shuechanismImplemenedHerein
 };
 epicsShareFunc enum epicsSocketSystemCallInterruptMechanismQueryInfo