patch applied (packages/array): FIX BUILD: build-depends should be inside library { ... }

[Malcolm Wallace]

>   * FIX BUILD: build-depends should be inside library { ... }

Apologies for breaking the ghc build on this.

But is there a good rationale for this restriction?  It seems obvious to
me that, in a cabal file with a library{} and possibly many executable{}
stanzas, one may wish to common-up some of those fields that appear
frequently, rather than duplicate them in each stanza.

Regards,
    Malcolm