ocaml-merlin, merlint: adapt to upstream 5.7 API changes
Query_protocol.Enclosing now takes Msource.position * Msource.position
option instead of just Msource.position (merlin 5.7.0). Pass [None]
for the optional end bound to match the single-point query behavior
our enclosing helper needed.
merlint/lib/dune.ml caught Sexp.Error.Error, but Sexp.Error is the
Textloc.Error module and the exception is Textloc.Error, not a
constructor inside it. Catch Textloc.Error directly and depend on
the textloc library explicitly.