git-gui: Don't translate the special Apple menu

git-gui: Don't translate the special Apple menu

Peter Karlsson pointed out there is no value in translating the
string "Apple", as this is used as the dummy label for the Apple
menu on Mac OS X systems.

The Apple menu is actually not the menu with the Apple corporate
logo, but the menu next to it, which shows the name of the
application and is typically called the application menu.  Most users
of git-gui see this menu titled as "Git Gui".  The actual label of
this menu comes from our Info.plist file and cannot be specified
by any other means.  Translating this string in the Tcl PO files
is not necessary.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>