devel/py-dateutil: Remove use of dos2unix

The file installed as dateutil-zoneinfo.tar.gz is corrupted by the dos2unix
run on all of the files in the distribution. There is no need to run dos2unix
as the only files with CRLF is the NEWS file, a README and a Windows BAT file
(which makes sense to use CRLF).

Accordingly:

• Remove use of USES=dos2unix
• Bump PORTREVISION to rebuild package (containing corrupted TZ data file)

PR: 217264
Submitted by: gordon
MFH: 2017Q2