Just a few thoughts

Wavelet-decompose was a package request a couple of weeks ago on the PCLOS forum. Packager said "The plugin doesn't work on my x86_64 but I could see it on GIMP's Tools on my i586 so I'm not packaging it. However, I did manage to compile the binary for it."

maybe this has a bearing on your problem.

Some one else confirmed that the 386 binary provided did not work on their 64 bit installation. - not surprising.

I use 32 bit and the binary works fine on my gimp 2.8 RC1 - popped it into my local plugins.
but then,
it is not a complicated plugin and the debian compilation from the gimp-registry-plugins package also works just as well & this is definitely not a debian machine.

There are 32 & 64 bit packages available just unpack the .deb and copy to your plugins folder. Make sure it is executable. Worth a try.
http://packages.debian.org/squeeze/gimp-plugin-registry

If you desperately need wavlet-decompose and until you get your compilation sorted, there is a script that works.
http://registry.gimp.org/node/13549 the order of the layers is a bit different but no great hurdle.

I have great sympathy with your efforts, a few days ago I compiled the gimp-image-register plugin and that was a similar pain even though I have my 2.8RC1 in /users rather than /opt.

Thanks, I'll try those out if I can't manage to compile this...