(Qt5) Modified ProcessByBrick::BlockingReportProgress to unlock QMutex before...

(Qt5) Modified ProcessByBrick::BlockingReportProgress to unlock QMutex before it is destroyed. This fixes extraneous output in app tests. Modified findfeatures' QDebugLogger so /dev/null is not opened with append mode.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/v006LibrariesV2@6710 41f8697f-d340-4b68-9986-7bafba869bb8