The return code of the command line version of
checkstyle returns the number of errors when the
checkstyle process exits.
This creates problems when integrating checkstyle as a
rule in a makefile because make interprets the non zero
return code as a failure and stops the build.
This can be worked around by prefixing the java command
line with a minus but it would be nice not to have to
ignore the return code and instead use the return code
to determine whether checkstyle ran successfully or not.