[Bug sanitizer/79341] Many Asan tests fail on s390

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79341

--- Comment #47 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Seems clang doesn't default to -mbackchain for -fsanitize=address, they just
force it on when testing:
if config.target_arch == 's390x':
  clang_asan_static_cflags.append("-mbackchain")

So, if we just want to go that route, we could add to deep-stack-uaf-1.C
// { dg-additional-options "-mbackchain" { target { s390*-*-* } } }

It is of course not very kind to users that would need to add it manually if
they want accurate backtraces for malloc/free.