qa/338: handle missing NOTICES file correctly
qa/338: handle missing NOTICES file correctly

Needed guards ahead of the mv(1) commands.

Found while testing the recent pmpost(1) changes.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp