verify-uselistorder: More outs() and errs(), less dbgs()

Change all the normally relevant output in `verify-uselistorder` from
using `dbgs()` to using `outs()` and `errs()`.  Now you don't need
`-debug=uselistorder` to figure out what's going on (or at what stage
verification failed, or to get the paths of the left-behind temporary
files).  This is a debugging tool, so I put the logging messages on
`outs()` and the error messages on `errs()`.

I also adjusted the output to be less ***loud***.  Not sure why I was so
`*`-happy when I first wrote this.

llvm-svn: 234929