Ok... I added chromicant's 5 line patch for byteswap.h which seems to have worked (as far as I can tell), but I then ran into a libcurl problem shown here:
checking for curl-config... /sw2/bin/curl-config
checking for the version of libcurl... 7.21.2
checking for libcurl >= version 7.10.1... yes
checking whether libcurl is usable... no
configure: error: Missing required libcurl >= 7.10.1
As far as I can tell libcurl was install correctly, but I reinstalled it from fink (
http://pdb.finkproject.org/pdb/package.php/libcurl4?rel_id=10.6-x86_64-current-stable) and when that didn't work, I rebuilt it from the latest source (7.21.4;
http://curl.haxx.se/download.html). I am not sure if there is something strange or broken about this machine so I will try to compile on another, fresher Mac tomorrow. Curl -v gives:
curl 7.21.2 (i386-apple-darwin10.6.0) libcurl/7.21.2 OpenSSL/0.9.8l zlib/1.2.3 c-ares/1.7.3 libssh2/1.2.7 librtmp/2.3