graphics/zint: distfile had been rerolled, update the port accordingly

-5492511 May 24 20:26 zint-2.11.0-src.tar.gz (old)
+5493656 May 25 09:58 zint-2.11.0-src.tar.gz (new)

The old distfile contents is identical to the new one, but was missing
the container directory (hence the need for NO_WRKSUBDIR). While here,
chase HTTP/1.1 301 redirection in the WWW line of the port description.

Reported by: pkg-fallout