Minimum GMP/MPFR version bumps for GCC-4.5

[Kaveh R. Ghazi]

Hi,

I'd like to open the issue of minimum GMP/MPFR versions for gcc-4.5.  We 
currently require gmp-4.1 and mpfr-2.3.0 to build GCC.

Part of my motivation is that MPC requires more recent versions of these 
packages.  But also older GMP/MPFR have known bugs and I'd like to encourage 
upgrading to less ancient versions.  E.g. on x86_64-unknown-linux-gnu, you 
can't even build gmp-4.1.1, it gets some kids of assembler error midway 
through.

So I'd like to bump the minimum required GMP version to 4.2.  According to 
the datestamps in http://ftp.gnu.org/gnu/gmp/ the 4.2.0 package has been out 
since at least March 2006.  It usually takes a year to release GCC so by the 
time gcc-4.5 is out, gmp-4.2.x will have been available for four years.

I'd like to bump MPFR from 2.3.0 to 2.3.1.  There are several bugs in the 
2.3.0 release that are exposed by the way MPC uses MPFR.  Upgrading to 
version 2.3.1 fixes these issues.  MPFR 2.3.0 was released in sept 2007, the 
2.3.1 release was available 5 months later in Jan 2008.  So by the time 
gcc-4.5 is out, it will have been released for at least two years.

If there are no objections, I'll create a patch.

       Thanks,
       --Kaveh
--
Kaveh R. Ghazi