Add a handler to log UART data

This change adds a new handler, to log UART data to a size-limited log
file.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/Makefile b/Makefile
index 544e18a..ed46115 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@
 
 all: console-server
 
-console-server: console-server.o util.o stdio-handler.o
+console-server: console-server.o util.o stdio-handler.o log-handler.o
 
 clean:
 	rm -f console-server *.o