[PATCH] gitk: Bind keyboard actions to the command key on Mac OS

[PATCH] gitk: Bind keyboard actions to the command key on Mac OS

git-gui already uses the command key for accelerators, but gitk has
never done so.  I'm actually finding it very hard to move back and
forth between the two applications as git-gui is following the Mac
OS X conventions and gitk is not.

This trick is the same one that git-gui uses to determine which
key to bind actions to.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>