After #26608 I got a report about missing rpaths when building a
downstream package independently using a spack-installed toolchain
(@tmdelellis). This occurred because the spack-installed libraries were
being linked into the downstream app, but the rpaths were not being
manually added. Prior to #26608 autotools-installed libs would retain
their hard-coded path and would thus propagate their link information
into the downstream library on mac.
We could solve this problem *if* the mac linker (ld) respected
`LD_RUN_PATH` like it does on GNU systems, i.e. adding `rpath` entries
to each item in the environment variable. However on mac we would have
to manually add rpaths either using spack's compiler wrapper scripts or
manually (e.g. using `CMAKE_BUILD_RPATH` and pointing to the libraries of
all the autotools-installed spack libraries).
The easier and safer thing to do for now is to simply stop changing the
dylib IDs.
9cfecec002