The "remove configure macro (built problem)" change in gmp 4.3.1-1 has caused it to be built without $RPM_OPT_FLAGS: http://kojipkgs.fedoraproject.org/packages/gmp/4.3.1/1.fc12/data/logs/x86_64/build.log See bug 496968 for more info.
Thanks, fixed in gmp-4.3.1-2.fc12.
Unfortunately the 4.3.1-2 Rawhide build was bitten by bug 505774: http://kojipkgs.fedoraproject.org/packages/gmp/4.3.1/2.fc12/data/logs/x86_64/build.log A simple bump and rebuild should fix it.
Thanks, rebuild.