[Bug c/108896] provide "element_count" attribute to give more context to __builtin_dynamic_object_size() and -fsanitize=bounds

[kees at outflux dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896

--- Comment #1 from Kees Cook <kees at outflux dot net> ---
The corresponding Clang feature request is here:
https://github.com/llvm/llvm-project/issues/60928