Multicore OCaml: June 2021

[cvine]

@avsm

The OCaml standard library was made safe for parallel use by multiple domains (wiki , issue, fixes ); and in particularly the Format and Random modules.

As a point of information, does that include the Str module, which seems obviously unsafe unless its stored state is thread local? (I am not making a special case for Str, as Re already provides a more capable alternative.)