Turning compilation.txt into an automated test

[Chong Yidong]

Now that ERT is present in Emacs, it would be nice to convert the
compilation-mode tests in etc/compilation.txt into something automated.
Currently, this file requires a developer to scan through dozens of
compiler messages looking for mistaken highlighting, a ridiculous task.
Indeed this part of Emacs has been plagued by regression bugs, so an
automated test would be valuable.

Is anyone interested in taking on this job?