[PATCH:twm] Remove unused fallback implementation of putenv()

[Mark Kettenis]

> From: Alan Coopersmith <alan.coopersmith at oracle.com>
> Date: Mon,  9 May 2011 22:51:36 -0700
> 
> NOPUTENV was never defined in a modular build, probably because putenv()
> is a standard function in Unix98 / SUSv2.

Much older than that.  Looks like it first appeared in SVR2 and
4.3BSD-Reno.  That should mean that everything that's even remotely
UNIX these days should have it.

Reviewed-by: Mark Kettenis <kettenis at openbsd.org>

> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
> ---
>  src/util.c |   66 ------------------------------------------------------------
>  1 files changed, 0 insertions(+), 66 deletions(-)