I suspect (or at least wonder if) the FTBFS on petsc [1] might be relevant to this discussion. I haven't had time to debug fully, but petsc started failing to build on Tier 2 architectures after the pie defaults changed. petsc builds libraries, so the build explicitly uses -fPIC. Currently of the 2nd tiers arches, only hppa builds successfully (alpha also, until the most recent build).
The failure occurs at configure time when the build checks the shared library linker. [1] https://buildd.debian.org/status/package.php?p=petsc&suite=unstable
