Mystery solved... GCC 4.8 does not provide a symbolizer.
From a new comment on the GCC bug report (https://bugzilla.redhat.com/show_bug.cgi?id=1250844#c6):
Even with symbolizer you may face some issue with ASAN on ARM. Check this llvm bug report [1].
Thanks, that makes sense. I could not understand why code that had been stable for nearly 20 years was producing a finding under GCC 4.8 Asan.
The next mystery is why its producing a finding at all.
Jeff