[CMake] quieter recompiles

[Brad King]

Joshua Blocher wrote:
> After I have built my project and I update some of the project.
> it spits out a bunch of lines with the percents even if the file has
> been already compiled. Is there anyway to make its progress
> updated on one line unless it has to re-compile something.

It used to be totally quiet but people complained that for big projects
they could not tell if anything was happening.  Currently it prints one
line per target unless something needs to build.  Are you seeing more
than this?

-Brad