MFH: r413476

• fix scoreboard, backport fix from [1]
• bump PORTREVISION

For details see discussion:
http://mail-archives.apache.org/mod_mbox/httpd-dev/201604.mbox/browser

Thanks to Ken J. for reporting the issue and testing the patch!

Reported by: Ken J. (on apache@ list)
Obtained from: http://home.apache.org/~ylavic/patches/scoreboard-2.4.18.diff [1]

Approved by: ports-secteam (junovitch@)