server: ensure per-cycle buffer is smaller than ringbuffer

... otherwise there's a chance we can't queue a full read.

Change-Id: I7bae8b124a523aac39045b6da97b486924e69f97
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/console-server.c b/console-server.c
index 50ee82a..fb84e19 100644
--- a/console-server.c
+++ b/console-server.c
@@ -475,6 +475,8 @@
 	for (;;) {
 		uint8_t buf[4096];
 
+		BUILD_ASSERT(sizeof(buf) <= buffer_size);
+
 		if (sigint) {
 			fprintf(stderr, "Received interrupt, exiting\n");
 			break;