[RFC] Update minimum make version to 3.81

[Joseph Myers]

On Fri, 10 Jun 2016, Mike Frysinger wrote:

> On 10 Jun 2016 15:27, Roland McGrath wrote:
> > eval is a pretty horrible feature and I'd probably object to introducing
> > any uses of it into libc's makefiles.  We already have lots of things that
> > might have been done that way, but are instead done with generated makefiles.
> 
> while i agree, i still think we should raise the min make ver.
> practically speaking, no one is testing 3.79 or 3.80.
> 
> i wouldn't mind 3.82 myself -- that's 2010.  our gcc & binutils
> requirements are more recent than that.

It took a long time for GNU/Linux distributors to move on from 3.81.  For 
example, Ubuntu 14.04 uses 3.81.

-- 
Joseph S. Myers
joseph@codesourcery.com