BTW, a couple other things that should be noted here:
* Per observation in a nearby thread, install_name_tool seems to
be provided by Apple's "Command Line Tools", but not by Xcode.
This is also true of bison and flex, but we don't require those
in a build-from-tarball. So relying on install_name_tool would
represent an expansion of our requirements for end-user builds.
I don't think this is a fatal objection, not least because the
CLT are a great deal smaller than Xcode --- so we likely ought to
encourage people to install just the former. But it's a change.
* By chance I came across a previous thread in which someone
suggested use of install_name_tool:
https://www.postgresql.org/message-id/flat/CAN-RpxCFWqPXQD8CqP3UBqdMwUgQWLG%2By7vQgxQdJR8aiKB89A%40mail.gmail.com
I griped in that thread that it didn't help for test executables
that don't get installed, such as isolationtester, because the
hack never got applied to them. Re-reading Peter's patch with
that in mind, I see he replaces the path in isolationtester
in-place, which means that it works in "make check" but will
fail in "make installcheck". So I'm not sure how to cope
with that, but it's a problem.
regards, tom lane