Build only ppc binaries in the Default configuration.

Build only ppc binaries in the Default configuration.

I'm using an Intel-processor Mac here, and Xcode defaults to building only
the native i386 binary.  However, the bundled iLifeControls.framework has
been built for ppc only, so the resulting MacTF.app fails to load
iLifeControls.framework, uses Apple classes instead, and then crashes due
to an unrecognized ObjC selector.  With this change, I get a runnable ppc
binary on the Intel-processor Mac too.

[Session started at 2007-10-18 08:47:36 +0300.]
2007-10-18 08:47:36.386 MacTF[2714] Unknown class NFIButton in Interface Builder file.
2007-10-18 08:47:36.417 MacTF[2714] Unknown Window class NFIWindow in Interface Builder file,
	 creating generic Window instead
2007-10-18 08:47:36.567 MacTF[2714] *** -[NSWindow setTitleBarHeight:]: selector not recognized [self = 0x35c600]
2007-10-18 08:47:36.568 MacTF[2714] An uncaught exception was raised
2007-10-18 08:47:36.578 MacTF[2714] *** -[NSWindow setTitleBarHeight:]: selector not recognized [self = 0x35c600]
2007-10-18 08:47:36.578 MacTF[2714] *** Uncaught exception: <NSInvalidArgumentException> *** -[NSWindow setTitleBarHeight:]: selector not recognized [self = 0x35c600]