event-notifier: Add "is_external" parameter

All callers pass "false" keeping the old semantics. The windows
implementation doesn't distinguish the flag yet. On posix, it is passed
down to the underlying aio context.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

stubs/set-fd-handler.c

@@ -9,3 +9,13 @@ void qemu_set_fd_handler(int fd,
 {
     abort();
 }
+
+void aio_set_fd_handler(AioContext *ctx,
+                        int fd,
+                        bool is_external,
+                        IOHandler *io_read,
+                        IOHandler *io_write,
+                        void *opaque)
+{
+    abort();
+}