pragma change breaks build

[David Miller]

From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 27 Apr 2015 15:43:52 -0700

> David Miller wrote:
>> instead of just adding a "= 0" initializer to vallen so
>> that all gcc's will not warn
> 
> That could cause glibc to have a useless machine instruction, no?
> Horrors!

Good you thought about that since setenv() is a performance critical
library routine...

> Does the attached patch work for you?

I'll give this a test later, thanks.