Reduce noise when calling the checkpolicy command line. In Android, this
creates unnecessary build noise which we'd like to avoid.
https://en.wikipedia.org/wiki/Unix_philosophy
Rule of Silence
Developers should design programs so that they do not print
unnecessary output. This rule aims to allow other programs
and developers to pick out the information they need from a
program's output without having to parse verbosity.
An alternative approach would be to add a -s (silent) option to these
tools, or to have the Android build system redirect stdout to /dev/null.
Signed-off-by: Nick Kralevich <nnk@google.com>