I've just gotten 2.1.4 to build on Solaris 8/SPARC with the Sun Forte 6.1 C compiler. There were problems with about 5 files, some having to do with __attribute__ (which someone else recently mentioned), and some having to do with void pointer arithmetic.
I can submit patches if desired, but can't vouch for their portability. Interestingly, I had a whole different set of problems when I tried to use gcc 3.0.4 - enough so that it seemed easier to switch back to cc and make these patches rather than investigate. (I'm in a time crunch, so I apologize for providing such a vague report.) Steve