introduce target tmpnam and require it in tests relying on it

[Jeff Law]

On Tue, 2020-04-28 at 20:43 -0300, Alexandre Oliva wrote:
> On Apr 28, 2020, Bernhard Reutner-Fischer <rep.dot.nop@gmail.com> wrote:
> 
> > ISTM the corresponding documentation hunk for sourcebuild.texi  is missing.
> 
> Thanks, I wasn't aware that testsuite effective targets were documented
> there.
> 
> Here's the missing documentation.  Tested with 'make info' on
> x86_64-linux-gnu.  Ok to install?
> 
> 
> document effective target fileio
> 
> From: Alexandre Oliva <oliva@adacore.com>
> 
> check_effective_target_fileio was added to
> gcc/testsuite/lib/target-supports.exp the other day, without
> documentation.
> 
> This patch adds the corresponding documentation.
> 
> 
> for  gcc/ChangeLog
> 
> 	* doc/sourcebuild.texi (Effective-Target Keywords): Document
> 	the newly-introduced fileio effective target.
OK
jeff
>