HEAD does not build on OS X using 7.2.1 as bootstrap compiler

[Johan Tibell]

Here's the error I get:

compiler/nativeGen/PprBase.hs:26:8:
    Could not find module `Data.Array.Unsafe'
    Perhaps you meant
      Data.Array.Base (from array-0.3.0.3)
      Data.Array.Unboxed (from array-0.3.0.3)
    Use -v to see a list of the files searched for.

This is from a clean tree.