Luv 0.5.12

Breaking

• Luv.Passwd.t.uid and Luv.Passwd.t.gid are now unsigned longs, in accordance with a change in libuv (#147).

Additions

• Upgrade vendored libuv to 1.44.2 (#147).
• Expose uv_available_parallelism as Luv.System_info.available_parallelism (#147).

Bugs fixed

• uv_buf_t::len is a size_t (Christiano Haesbaert, #133).
• Parse host: config correctly during build (reported by Pablo Meier and Matthieu Gosset, #138).
• Define CAML_NAME_SPACE before including OCaml headers (Antonin Décimo, #139).
• Register references to callbacks in trampolines that allocate (reported by Thomas Leonard, #145). The way this bug was fixed requires OCaml 4.03.