After playing around for a while, I discovered that the true culprit in the ld crime syndicate was libtiff. For reasons that escape me (and about 4000 other people, from what I can see on Google) the tiff library silently ignores ld errors. It wasn't until I looked at the config.log file that I noticed them.
This appears to be true whether I build with GNU ld or Sun ld, although the errors are slightly different. There is no easy solution except, of course, to rip the tiff library off my system altogether, which is exactly what I did. As far as I can tell, the damn thing is just broke on Solaris.
Things seem to be building fine now. :)
