Restore support for OCaml 4.02

src/benchmark/fastRand/jbuild

@@ -6,5 +6,4 @@
   (c_names (fast_rand))
   (c_flags (:standard -O3))
   (flags (:standard -w -3))
-  (ocamlopt_flags (:standard -O3))
 ))

src/benchmark/jbuild

@@ -1,10 +1,14 @@
+(* -*- tuareg -*- *)
+
+let config = {|
+
 (jbuild_version 1)
 
 (executable
  ((name main)
   (libraries (capnp fast_rand core))
   (flags (:standard -w -27-53-55-3-35))
-  (ocamlopt_flags (:standard -O3 -inline 2000))
+  (ocamlopt_flags (:standard # -inline 2000))
 ))
 
 (rule
@@ -41,3 +45,15 @@
  ((name benchmarks)
   (deps (carsales catrank eval))
 ))
+
+|}
+
+let () =
+  let hash = String.index config '#' in
+  let opt = if Jbuild_plugin.V1.ocaml_version >= "4.03" then "-O3" else "" in
+  let config =
+    String.sub config 0 hash ^
+    opt ^
+    String.sub config (hash + 1) (String.length config - hash - 1)
+  in
+  Jbuild_plugin.V1.send config

src/runtime/jbuild

@@ -1,3 +1,7 @@
+(* -*- tuareg -*- *)
+
+let config = {|
+
 (jbuild_version 1)
 
 (library (
@@ -6,5 +10,17 @@
   (synopsis "Runtime support library for capnp-ocaml")
   (libraries (core_kernel uint ocplib-endian res extunix))
   (flags (:standard -w -50-27-6-34-32-53-33))
-  (ocamlopt_flags (:standard -O3 -inline 1000))
+  (ocamlopt_flags (:standard # -inline 1000))
 ))
+
+|}
+
+let () =
+  let hash = String.index config '#' in
+  let opt = if Jbuild_plugin.V1.ocaml_version >= "4.03" then "-O3" else "" in
+  let config =
+    String.sub config 0 hash ^
+    opt ^
+    String.sub config (hash + 1) (String.length config - hash - 1)
+  in
+  Jbuild_plugin.V1.send config