postgresql: add ldapSupport option

pkgs/servers/sql/postgresql/generic.nix

@@ -59,6 +59,10 @@ let
       , nukeReferences
       , overrideCC
 
+      # LDAP
+      , ldapSupport ? false
+      , openldap
+
       # PAM
       , pamSupport ? stdenv.hostPlatform.isLinux
       , linux-pam
@@ -145,7 +149,8 @@ let
       ++ lib.optionals pythonSupport [ python3 ]
       ++ lib.optionals gssSupport [ libkrb5 ]
       ++ lib.optionals pamSupport [ linux-pam ]
-      ++ lib.optionals perlSupport [ perl ];
+      ++ lib.optionals perlSupport [ perl ]
+      ++ lib.optionals ldapSupport [ openldap ];
 
     nativeBuildInputs = [
       makeWrapper
@@ -187,7 +192,8 @@ let
       # This could be removed once the upstream issue is resolved:
       # https://postgr.es/m/flat/427c7c25-e8e1-4fc5-a1fb-01ceff185e5b%40technowledgy.de
       ++ lib.optionals (stdenv'.hostPlatform.isDarwin && atLeast "16") [ "LDFLAGS_EX_BE=-Wl,-export_dynamic" ]
-      ++ lib.optionals (atLeast "17" && !perlSupport) [ "--without-perl" ];
+      ++ lib.optionals (atLeast "17" && !perlSupport) [ "--without-perl" ]
+      ++ lib.optionals ldapSupport [ "--with-ldap" ];
 
     patches = [
       (if atLeast "16" then ./patches/relative-to-symlinks-16+.patch else ./patches/relative-to-symlinks.patch)