Moved depexts to PostgreSQL configuration package

Author: mmottl

postgresql.opam

@@ -22,20 +22,7 @@ depends: [
   "base" {build}
   "stdio" {build}
   "base-bytes"
-]
-
-depexts: [
-  ["libpq-dev"] {os-distribution = "debian"}
-  ["database/postgresql96-client"] {os-distribution = "freebsd"}
-  ["database/postgresql96-client"] {os-distribution = "openbsd"}
-  ["libpq-dev"] {os-distribution = "ubuntu"}
-  ["postgresql-devel"] {os-distribution = "centos"}
-  ["postgresql-devel"] {os-distribution = "rhel"}
-  ["postgresql-devel"] {os-distribution = "fedora"}
-  ["postgresql-devel"] {os-distribution = "opensuse"}
-  ["postgresql-dev"] {os-distribution = "alpine"}
-  ["postgresql"] {os = "macos" & os-distribution = "homebrew"}
-  ["postgresql96"] {os = "macos" & os-distribution = "macports"}
+  "conf-postgresql" {build}
 ]
 
 synopsis: "Bindings to the PostgreSQL library"