reclassify `cat()` statements in `compile()`

[wpetry]

There is no way to suppress statements produced by compile() because they use cat() instead of message(), warning(), etc. Wrapping the function with invisible(compile(...)) still reports the path to Makevars.

Reclassifying these informational statements would allow these to be suppressed by the user. This would be particularly helpful for tutorials where printed statements can be confusing to users.