Cocoa: Fix compilation on Mac OS X v10.4 and earlier

Cocoa: Fix compilation on Mac OS X v10.4 and earlier

NSView's enterFullScreenMode:withOptions: and
exitFullScreenModeWithOptions: are available on v10.5
and later only. Undefined methods raise warnings and
undefined constants result in errors.

Reported by Ryan Schmidt.

While at it, avoid a warning on v10.3.9,
where MAC_OS_X_VERSION_10_4 is not defined.

Spotted by John Arbuckle.

Fix associated comments.

Signed-off-by: Andreas Färber <[email protected]>
Cc: John Arbuckle <[email protected]>
Cc: Ryan Schmidt <[email protected]>
Cc: Mike Kronenberg <[email protected]>
Signed-off-by: malc <[email protected]>