Still looking for a review of this small patch to help detect
potentially unsafe calls to __builtin_{frame,return}_address
(with an argument > 2) that tend to either return bogus values
or lead to crashes at runtime.The problem the function can cause was originally reported in pr8743 and resolved by adding a note to the documentation. This patch tweaks the documentation further to make the risks of using the function that much clearer. https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00886.html Thanks Martin
