Since xpidl is shipped with the sdk it should be statically linked to avoid depending on specific versions of libraries being available on the users machine. Currently the mac version for instance relies on libintl.3.dylib being present since that is what is there on the mac reference platform. However it appears to be impossible to compile this version on leopard. It is possible to symlink to victory but it'd be better to just avoid this.
Apparently this isn't possible since the appropriate versions of all the libraries aren't available generally :(
I've added documentation providing workarounds for this bug on MDC: http://developer.mozilla.org/en/docs/Gecko_SDK#Issues_with_the_OS_X_SDK