sakura-3.0.4-1 is not built with $RPM_OPT_FLAGS: http://kojipkgs.fedoraproject.org/packages/sakura/3.0.4/1.fc19/data/logs/x86_64/build.log 2.4.2-4 did not have this problem.
Thanks for the haeds-up!
Submitted upstream as https://bugs.launchpad.net/fedora/+source/sakura/+bug/1058717 Meanwhile, I am using sed to change the flags in CMakeLists.txt.
sakura-3.0.4-2.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/FEDORA-2012-14946/sakura-3.0.4-2.fc18