h1: handle LRS_FLUSHING_BEFORE_CLOSE at ops read

read has a tight leash on the states it's happy to turn up there,
it's good to be like that but it turns out LRS_FLUSHING_BEFORE_CLOSE
should be whitelisted since it can happen under some transient
conditions and is valid.

https://github.com/warmcat/libwebsockets/issues/1872
diff --git a/lib/roles/h1/ops-h1.c b/lib/roles/h1/ops-h1.c
index bc9de63..8e10080 100644
--- a/lib/roles/h1/ops-h1.c
+++ b/lib/roles/h1/ops-h1.c
@@ -256,6 +256,9 @@
 	case LRS_SSL_ACK_PENDING:
 		break;
 
+	case LRS_FLUSHING_BEFORE_CLOSE:
+		break;
+
 	case LRS_DEAD_SOCKET:
 		lwsl_err("%s: Unhandled state LRS_DEAD_SOCKET\n", __func__);
 		goto bail;