Description of problem:

# rpm -V glibc-devel
missing     /usr/lib/librt.so.1

Indeed, 'rpm -qvl glibc-devel | grep /librt' shows
/usr/lib/librt.so.1 -> librtkaio.so

The catch is that there is no /usr/lib/librtkaio.so.  One can
find /usr/lib/librtkaio.a and /lib/rtkaio/librtkaio-2.5.so and
/lib/rtkaio/i686/nosegneg/librtkaio-2.5.so (that last one on 'i686')
but no librtkaio.so anywhere so that link is difficult to "repair".

Consequences for linking with -lrt are easy to predict although
a presence of /usr/lib/librt.a, interestingly enough different than
/usr/lib/librtkaio.a, surely helps. :-)

Version-Release number of selected component (if applicable):
glibc-2.5-3