[Bug libgcc/91053] __builtin___clear_cache can fail

[oth+gccbugs at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91053

--- Comment #2 from Orion Hodson <oth+gccbugs at google dot com> ---
For sure the goal wasn't to suggest that this was due to a privileged
operation.