[Nix-dev] Recent change to stdenv in 4cb43d2

[John Wiegley]

My apologies to all for changing stdenv everwhere by merging 4cb43d2 without
waiting to batch it with other, pending stdenv changes.  It was a minimal,
correct fix to the way ppl is compiled, but shouldn't have been merged in by
itself.

If it should be reverted, can someone please do so?  I'm flying to Boston
today and will be out of contact.

John