Replying to pmetzger:
This works under current Xcode.
No doubt! But apparently the version of ld on Snow Leopard is too old to know about -export_dynamic. (I was mistaken earlier when I thought it was due to the old compiler because I saw /usr/bin/gcc-4.2 on the line, but -Wl,-export_dynamic means "pass -export_dynamic to the linker", so it's actually the old linker that's causing the problem.)
Ideally, the configure script should first check whether the linker understands a flag before trying to use it. That's the purpose of configure scripts: to determine the capabilities of the system and not make assumptions. Looking at configure.ac, it's unconditionally using -Wl,-export_dynamic on macOS.
