It looks like Nettle is no longer building or installing hogweed on some Apple platforms.
This is from a PowerMac G5 running OS X 10.5:
$ ls /usr/local/lib | grep -E 'gmp|nettle|hogweed' libgmp.10.dylib libgmp.a libgmp.dylib libgmp.la libnettle.8.2.dylib libnettle.8.3.dylib libnettle.8.dylib libnettle.a libnettle.dylib libpari-gmp.dylib
It is causing a failure in GnuTLS:
checking for NETTLE... yes checking for HOGWEED... no configure: error: *** *** Libhogweed (nettle's companion library) 3.4.1 was not found. Note that you must compile nettle with gmp support.
Jeff