Add HAVE_EVENT_BASE_LOOPEXIT to win32/orconfig.h

Fix for bug 7308

src/win32/orconfig.h

@@ -249,3 +249,4 @@
 #define HAVE_EVENT2_EVENT_H
 #define SHARE_DATADIR ""
 #define HAVE_EVENT2_DNS_H
+#define HAVE_EVENT_BASE_LOOPEXIT