www/chromium: Add a script for automating the hanging tabs workaround

[0mp]

Summary

At the moment pkg-message says that in order to work around the hanging tabs problem the user may wish to run the following commands:

# [ -d ~{user}/.cache/chromium ] || mkdir ~{user}/.cache/chromium
# echo "md $(echo ~{user})/.cache/chromium mfs rw,late,-w{user}:{group},-s300m 2 0" >> /etc/fstab
# mount ~{user}/.cache/chromium

This patch adds a fix-hanging-tabs.sh script to the DATADIR, which simplifies the process to just running

/usr/local/share/chromium/fix-hanging-tabs.sh $user $group

[0mp]

Add a missing $FreeBSD$ line to the script.

[cpm]

Committed in r476599.

[0mp]

Close as it has been committed.