Fixed build by silencing unneeded warning.
Typo fix.
Fixed the xnu build procedure.

Xcode 5.1 changes the behavior of Run Script build phases, so that messages sent to stdout are displayed all at once, after the script has finished. (They used to be displayed in Xcode as they arrive.) This means that a message giving the location of the xnu build log file now doesn't show up until after xnu has finished building, which kind of defeats the point of its existence. I fixed this by moving the print statement into a separate build phase.