[PATCH 2/2] manual: Document __libc_single_threaded

[Szabolcs Nagy]

The 05/20/2020 20:12, Florian Weimer via Libc-alpha wrote:
> +@smallexample
> +if (__libc_single_threaded)
> +  atomic_fetch_add (&reference_count, 1, memory_order_relaxed);
> +else
> +  atomic_fetch_add (&reference_count, 1, memory_order_acq_rel);
> +@end smallexample
> +
> +This still requires some form of synchronization on the
> +single-threaded branch, so it can be beneficial not to declare the
> +reference count as @code{_Atomic}, and use the GCC @code{__atomic}
> +built-ins.  @xref{__atomic Builtins,, Built-in Functions for Memory
> +Model Aware Atomic Operations, gcc, Using the GNU Compiler Collection
> +(GCC)}.  Then the code to increment a reference count looks like this:
> +
> +@smallexample
> +if (__libc_single_threaded)
> +  ++refeference_count;inf

inf typo