Don't use -Wno-uninitialized in math/

[Steve Ellcey]

On Wed, 2015-08-26 at 21:18 +0000, Joseph Myers wrote:
> On Wed, 26 Aug 2015, Chris Metcalf wrote:
> 
> > Doing a tilegx build just now against the tip, I see something similar,
> > using gcc 4.8.2:
> > 
> > In file included from ../soft-fp/soft-fp.h:321:0,
> >                  from ../soft-fp/fmadf4.c:30,
> >                  from ../sysdeps/tile/s_fma.c:1:
> > ../soft-fp/fmadf4.c: In function Β‘__fmaΒ’:
> > ../soft-fp/op-common.h:274:10: error: Β‘R_eΒ’ may be used uninitialized in this
> > function [-Werror=maybe-uninitialized]
> 
> I wonder if it's something to do with macro locations, and moving the push 
> / ignore right up above the include of soft-fp.h helps (in which case 
> there isn't much point in the pop)?  It works for me as-is with GCC 5, but 
> given the various reports of problems, maybe it's too fragile and the 
> warning needs disabling for the whole file in soft-fp/fma*.c.

I tried moving the diag/ignore to just after the include of
libc-internal.h and I got errors about __GNUC_PREREQ not being defined.
If I put the diag/ignore's after the include of math.h (and
libc-internal.h) then things seemed to work.  Any idea why I need to
include math.h to get __GNUC_PREREQ defined?

Steve Ellcey
sellcey@imgtec.com