Appending to message buffer while in ddb

Hi there,

Since r226435, output from kernel printf/log functions is not appended 
to the message buffer when in ddb. The commit message doesn't call this 
out specifically; instead it appears to have been to address double 
printing to the console while in ddb. I noticed this because a ddb 
script which previously resulted in some things ending up in a 
textdump's msgbuf.txt no longer does so. It may be that the answer is 
"use db_printf in ddb", which is ok, but I thought I'd check anyway to 
see if the aforementioned change was indeed intentional, since I wasn't 
able to dig up any discussion about it.

Thanks,
Eric