[Bug sanitizer/88022] Support dynamic shadow offset in ASan

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88022

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The dynamic offset code has the problem that a) it is usually larger b) usually
slower c) ABI incompatible.