Add a new entry in `config.yaml`:
config:
shared_linking: 'rpath'
If this variable is set to `rpath` (the default) Spack will set RPATH in ELF binaries. If set to `runpath` it will set RUNPATH.
Details:
* Spack cc wrapper explicitly adds `--disable-new-dtags` when linking
* cc wrapper also strips `--enable-new-dtags` from the compile line
when disabling (and vice versa)
* We specifically do *not* add any dtags flags on macOS, which uses
Mach-O binaries, not ELF, so there's no RUNPATH)