run-program decodes and re-encodes environ

[Nikodemus Siivola]

...which is about as pointless as it gets. If environ is not explicitly provided as lisp strings, surely we should not start calling posix-environ.

More to the point, it makes things brittle unless c-string-external-format is anything but :latin-1 or another 8-bit encoding.

[Stas Boukarev (stassats)]

Here's my attempt, I modified it to pass NULL to spawn on the C side, and when spawn gets NULL, it leaves environ intact. I'm not entirely sure that it's the right way to go. But it works, and it also reduces consing.

[Stas Boukarev (stassats)]

commit 0395c15ff8394bfaaed03050c1a7a131f197a732
Author: Stas Boukarev <email address hidden>
Date: Tue May 22 22:06:06 2012 +0400

    run-program: Don't decode and re-encode environ.

    Leave environ unchanged when no :environment argument is provided.