Xcode: Teach BuildDepends test that Xcode >= 5 needs no help

Drop the HELP_XCODE workarounds needed on older Xcode versions when
using Xcode >= 5.  We now expect builds and rebuilds to work using
proper dependencies with no special help.
Merge topic 'xcode-5-no-BuildDepends-help'

7f459a6 Xcode: Teach BuildDepends test that Xcode >= 5 needs no help