mkrevision.sh: Unhyphenate git commands
mkrevision.sh: Unhyphenate git commands

- Use "git foo" rather than "git-foo", since git 1.6 will move the git-*
commands out of $PATH

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr