Fix dependency on sphinx

Julien LepillerSat Jul 20 10:31:04+0200 2019

870b74e

Fix dependency on sphinx

more/packages/ocaml.scm

4646
  #:use-module (gnu packages protobuf)
4747
  #:use-module (gnu packages python)
4848
  #:use-module (gnu packages python-xyz)
49+
  #:use-module (gnu packages sphinx)
4950
  #:use-module (gnu packages tex)
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  #:use-module (gnu packages texinfo)
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  #:use-module (more packages smt)