libCom: Fix cygwin socket shutdown issue.

Cygwin 1.7 changed the socket shutdown method from BothShutdown
to Close. This fix looks at the cygwin version to work out what
value to return from esscimqi().

src/libCom/osi/os/cygwin32/systemCallIntMech.cpp

@@ -0,0 +1,28 @@
+
+/*************************************************************************\
+* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
+*     National Laboratory.
+* Copyright (c) 2002 The Regents of the University of California, as
+*     Operator of Los Alamos National Laboratory.
+* EPICS BASE Versions 3.13.7
+* and higher are distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution. 
+\*************************************************************************/
+/* $Revision-Id$ */
+/*
+ *      Author:		Jeff Hill 
+ */
+
+#define epicsExportSharedSymbols
+#include "osiSock.h"
+
+enum epicsSocketSystemCallInterruptMechanismQueryInfo 
+        epicsSocketSystemCallInterruptMechanismQuery ()
+{
+#if (CYGWIN_VERSION_DLL_MAJOR >= 1007)
+    // Behaviour changed in Cygwin 1.7 release.
+    return esscimqi_socketCloseRequired;
+#else
+    return esscimqi_socketBothShutdownRequired;
+#endif
+}