Jim, that is great, you have got to the bottom of it ! Well done.
> Warning: ld: warning: -multiply_defined is obsolete
I assume its coming from the lazarus or LCL source, not your code ? Don't worry about it. Something is obsolete and will be removed, probably far into the future.
> Error: -macosx_version_min has been renamed to -macos_version_min
Sigh, this one, I believe, relates to your Mac install. It does not harm, try not to look at it. It relates to Mac dev tool kits, you have installed the whole thing rather that just the command line tools. Lots of mentions in previous forum posts.
So, for now, my advise is Mac users, use Lazarus stable, RC1 or Fixes. RC2 will almost certainly be replaced soon.
Davo