Did you remember to run (as root) ldconfig
after installing the libraries?
Although, I pulled open the kernel's makefile, and that seems unlikely to be the answer. You should probably do it anyway as a safeguard. The kernel is checking for a specific file when it prints that message. Specifically, it's looking for qconfig.h. It looks for (in this order):
You need to verify that file exists. If it doesn't, then qt-devel is not properly installed, or at least, not in one of the paths the kernel is looking for. Also, since your QTDIR is simply repeating one of the default search paths, you don't need to use it (unless the qconfig.h is in a different spot). If you do need to set QTDIR, it would be easier and cleaner to do something like this:
make xconfig QTDIR=/usr/lib/qt-3.3