vmm: serial_manager: Iterate again on EINTR

If the epoll_wait() call returns EINTR, this only means a signal has
been delivered before any of the file descriptors registered triggered
an event or before the end of the timeout (if timeout isn't -1). For
that reason, we should simply try to listen on the epoll loop again.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/serial_manager.rs

@@ -239,7 +239,7 @@ impl SerialManager {
                                     // returns an error of type EINTR, but this should not
                                     // be considered as a regular error. Instead it is more
                                     // appropriate to retry, by calling into epoll_wait().
-                                    0
+                                    continue;
                                 } else {
                                     return Err(Error::Epoll(e));
                                 }