In tracking down a solution to this on the mac developer forum, this seemed to be the popular answer:
This is a known issue in the Xcode 7 beta.   To work around this issue
  for now, please: Delete all references to .tbd files from either your
  linked libraries phase, or from the copied bundle resources phase
  (where they sometimes will be added). Add the library you want to link
  manually to the "Other Linker Flags" build settings, by adding the
  argument:
               -l
            for each library you want to link (for example, add "-lsqlite3" (without quotes)).   For those who are curious, the .tbd
  files are new "text-based stub libraries", that provide a much more
  compact version of the stub libraries for use in the SDK, and help to
  significantly reduce its download size.
In addition to this, I found that this worked verbatim for the sqlite3 example. But for libz.dylib you simply need to type -lz

And from there I was able to build successfully on the simulator, I have yet checked on a device running iOS9