Remove unused floating-point configuration from gmp-impl.h

[Florian Weimer]

* Joseph Myers:

> This patch removes the IEEE_DOUBLE_BIG_ENDIAN and
> IEEE_DOUBLE_MIXED_ENDIAN macros from gmp-impl.h and gmp-mparam.h, and
> the ieee_double_extract union from gmp-impl.h.  The macros were used
> only in defining the union, which was used nowhere in glibc.  As GMP's
> gmp-impl.h is over 5000 lines, the file in glibc is so far from the
> GMP version that it doesn't seem to make sense to keep things there
> that are not relevant in glibc.  (I expect there is plenty more in the
> header after this patch that is also not relevant in glibc and can be
> cleaned up later.)
>
> Tested with build-many-glibcs.py that installed stripped shared
> libraries are unchanged by this patch.

Thanks.  This looks okay to me.