Thanks for your help. I was able to solve this "myself" though, but had not yet posted the answer here.
The problem was not with the libraries for the target, but for the host. I had it installed on a 64-bit machine, and the libraries had to be 32 bit. It compiled fine after I installed the i686 versions of libz-devel and libmpc-devel.
There was something funny with the libz though. The compiler gave me errors, saying that it could not get the version information for zlib, unable to find the absolute file location. I was able to ls -l it though. It showed a symlink pointing from libz.so.1 to libz.so.1.x.x (I don't remember the exact version). I deleted and recreated this symlink, and it was fixed.
Now I just have to get qt working on the pi...