opam: camlp4 dependency

[vogler]

Currently installation fails for OCaml versions >= 4.02.0 with lwt installed, since camlp4 is no longer distributed with the compiler.

❯ opam install mongo
The following actions will be performed:
  ∗  install mongo 0.67.2

=-=- Gathering sources =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
[mongo] Archive in cache

=-=- Processing actions -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
[ERROR] The compilation of mongo failed at "ocaml setup.ml -configure --enable-lwt --prefix
        /Users/voglerr/.opam/4.04.1".
Processing  1/1: [mongo: ocamlfind remove]
#=== ERROR while installing mongo.0.67.2 ======================================#
# opam-version 1.2.2
# os           darwin
# command      ocaml setup.ml -configure --enable-lwt --prefix /Users/voglerr/.opam/4.04.1
# path         /Users/voglerr/.opam/4.04.1/build/mongo.0.67.2
# compiler     4.04.1
# exit-code    1
# env-file     /Users/voglerr/.opam/4.04.1/build/mongo.0.67.2/mongo-69339-1872ec.env
# stdout-file  /Users/voglerr/.opam/4.04.1/build/mongo.0.67.2/mongo-69339-1872ec.out
# stderr-file  /Users/voglerr/.opam/4.04.1/build/mongo.0.67.2/mongo-69339-1872ec.err
### stderr ###
# [...]
# File "setup.ml", line 5810, characters 31-50:
# Warning 3: deprecated: String.uncapitalize
# Use String.uncapitalize_ascii instead.
# File "setup.ml", line 5811, characters 31-48:
# Warning 3: deprecated: String.capitalize
# Use String.capitalize_ascii instead.
# ocamlfind: Package `lwt.syntax' not found
# W: Field 'pkg_lwt_syntax' is not set: Command ''/Users/voglerr/.opam/4.04.1/bin/ocamlfind' query -format %d lwt.syntax > '/var/folders/0j/1lq15k654zg7cf1rh9_gqty80000gn/T/oasis-478abe.txt'' terminated with error code 2
# E: Cannot find findlib package lwt.syntax
# E: Failure("1 configuration error")

After opam install camlp4 it succeeds.

[tsh-box]

I also got this error,how can I solve it?

[vogler]

After opam install camlp4 it succeeds.

[tsh-box]

Thanks you,

[msimon]

Sorry for the delay, I have more time now and will go over all the issues this weekend. Let me know if there anything missing as well.