Do not leave files behind in /tmp from testing

[Joseph Myers]

On Thu, 15 Oct 2015, Roland McGrath wrote:

> Since there is no controversy about the other changes in your patch,
> perhaps you should commit those separately so they are not conflated
> with the more complex issues raised by this one change.

I've done that, and added the general issue of reviewing add_temp_file / 
create_temp_file uses (of which there are many outside the preparation 
stage of tests) to 
<https://sourceware.org/glibc/wiki/Development_Todo/Master#Use_test-skeleton.c>.

-- 
Joseph S. Myers
joseph@codesourcery.com