build:update 'git review' config to match gerrit.minix3.org
We have moved the gerrit service to a new server and at the same time allowed
direct access to gerrit. This change updates the '.gitreview' file to reflect
these changes. If you have an existing checkout you might need to update your
.ssh/config file to remove the git-minix alias and edit .git/config to update
the gerrit repository from 'git-minix' to the new url sheme:
ssh://username@gerrit.minix3.org:2222/minix