re-add base-bytes and base-num

Author: hannesm

packages/base-bytes/base-bytes.backport/opam

@@ -0,0 +1,9 @@
+opam-version: "2.0"
+maintainer: " "
+authors: " "
+homepage: " "
+depends: [
+  "ocaml" {< "4.02.0"}
+  "ocamlfind" {>= "1.5.3"}
+]
+synopsis: "Bytes compatibility library distributed with ocamlfind"

packages/base-num/base-num.base/opam

@@ -0,0 +1,6 @@
+opam-version: "2.0"
+maintainer: "Xavier Leroy <[email protected]>"
+synopsis: "Num library distributed with the OCaml compiler"
+depends: [
+  "ocaml" {< "4.06.0"}
+]