Yet another "ld: symbol(s) not found for architecture x86_64" issue with boost, this time with mgiza
To address some of the concerns by the commenters: the best way to deal with this problem is to try and clear your system as much as possible and start the process from scratch.
Also, since this was posted, OS X 10.10 Yosemite was released, which may have fixed this problem (IIRC this problem is mostly due to 10.9 and the clang/gcc complier changes).