rss-glx 0.9.1p-1 is not built with $RPM_OPT_FLAGS, see the build log: http://kojipkgs.fedoraproject.org/packages/rss-glx/0.9.1.p/1.fc13/data/logs/x86_64/build.log 0.9.0.p-3 did not have this problem. %configuring with --disable-dependency-tracking could provide more readable build logs (e.g. make it easier to spot issues like this) and a possible slight speedup. See bug 496968 for more info.
built 0.9.1.p-2 which should fix this, should hit updates-testing shortly