Xcode 4.2 link error: libz issue?

Question

Moving a project to Xcode 4.2, I am getting a number of Mach-O linker unresolved errors, for things like _crc32, _expf, and _UnwindSjLj_Register, on a project that compiles

Answer 1

Had a problem with this same lib - libz.1.2.3.dylib. As suggested, I added libz.dylib. still got the message "ld: Library not found for -lz.1.2.3". Removed the reference build succeeded. Tried replacing libz.dylib with libz.1.2.5.dylib and still built without error. XCode 4.3.2, Lion (OS X 10.7.4)