bump min version of ocaml

Summary:
Came across when trying to compile infer on fresh VM.
Infer depends on reason now. Reason requires ocaml 4.02.3

Reviewed By: jberdine

Differential Revision: D3371378

fbshipit-source-id: 598c602

configure.ac

@@ -165,7 +165,7 @@ fi
 AC_PROG_OCAML
 AC_ASSERT_PROG([ocamlc], [$OCAMLC])
 # check the version of OCaml
-AC_ASSERT_OCAML_MIN_VERSION([4.02.1])
+AC_ASSERT_OCAML_MIN_VERSION([4.02.3])
 AC_ASSERT_PROG([ocamlopt], [$OCAMLOPT])
 AC_ASSERT_PROG([ocamlbuild], [$OCAMLBUILD])
 AC_PROG_FINDLIB