Gittrac #4361:  Added what should be a fix for this; need to do a
build/test on Windows to verify it...
Gittrac #4361:  Fixed .pl files that don't work on Windows -- Windows
doesn't like leading blank line or space between '#!' and
'/usr/bin/env'.
Gittrac #4361:  Added comments explaining tolerant_unlinks before
renames; added tolerant unlink when renaming old rescue DAG files.
Gittrac #4361:  Fixed related DAGMan tests that were failing on Windows
because of test problems (not DAGMan functionality).
Merge branch 'V8_2-gittrac_4361-branch' into V8_2-branch
Gittrac #4361:  Added version history item to 8.2.1.