BUG/MINOR: quic: break for error on sendto

If sendto returns an error, we should not retry the call and break from
the sending loop. An exception is made for EINTR which allows to retry
immediately the syscall.

This bug caused an infinite loop reproduced when the process is in the
closing state by SIGUSR1 but there is still QUIC data emission left.
diff --git a/src/quic_sock.c b/src/quic_sock.c
index 2cc5a7f..71fe0b7 100644
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -342,6 +342,7 @@
 		else if (ret == 0 || errno == EAGAIN || errno == EWOULDBLOCK || errno == ENOTCONN || errno == EINPROGRESS) {
 			/* TODO must be handle properly. It is justified for UDP ? */
 			qc->sendto_err++;
+			break;
 		}
 		else if (errno != EINTR) {
 			/* TODO must be handle properly. It is justified for UDP ? */