gnu: coq: Add search-paths for coq libraries.

* gnu/packages/ocaml.scm (coq)[native-search-paths]: New field.

gnu: Add ocaml-hex.

* gnu/packages/ocaml.scm (ocaml-hex): New variable.

gnu: Add ocaml-cstruct.

* gnu/packages/ocaml.scm (ocaml-cstruct): New variable.

gnu: Add ocaml-ocplib-endian.

* gnu/packages/ocaml.scm (ocaml-ocplib-endian): New variable.

gnu: Add ocaml-async.

* gnu/packages/ocaml.scm (ocaml-async): New variable.

gnu: Add ocaml-async-extra.

* gnu/packages/ocaml.scm (ocaml-async-extra): New variable.

gnu: Add ocaml-async-unix.

* gnu/packages/ocaml.scm (ocaml-async-unix): New variable.

gnu: Add ocaml-core.

* gnu/packages/ocaml.scm (ocaml-core): New variable.

gnu: Add ocaml-async-rpc-kernel.

* gnu/packages/ocaml.scm (ocaml-async-rpc-kernel): New variable.

gnu: Add ocaml-async-kernel.

* gnu/packages/ocaml.scm (ocaml-async-kernel): New variable.

gnu: Add ocaml-core-kernel.

* gnu/packages/ocaml.scm (ocaml-core-kernel): New variable.

Merge branch 'master' into staging

gnu: Add ocaml-ppx-jane.

* gnu/packages/ocaml.scm (ocaml-ppx-jane): New variable.

gnu: Add ocaml-ppx-expect.

* gnu/packages/ocaml.scm (ocaml-ppx-expect): New variable.

gnu: Add ocaml-re.

* gnu/packages/ocaml.scm (ocaml-re): New variable.

gnu: Add ocaml-ppx-fields-conv.

* gnu/packages/ocaml.scm (ocaml-ppx-fields-conv): New variable.

gnu: Add ocaml-ppx-sexp-message.

* gnu/packages/ocaml.scm (ocaml-ppx-sexp-message): New variable.

gnu: Add ocaml-ppx-custom-printf.

* gnu/packages/ocaml.scm (ocaml-ppx-custom-printf): New variable.

gnu: Add ocaml-ppx-fail.

* gnu/packages/ocaml.scm (ocaml-ppx-fail): New variable.

gnu: Add ocaml-ppx-bin-prot.

* gnu/packages/ocaml.scm (ocaml-ppx-bin-prot): New variable.