Mapserver 6.0.4 + PostGIS geography workaround for "function st_force_2d(geography) does not exist" error

ST_Force_2D-Geography.sql

CREATE OR REPLACE FUNCTION ST_Force_2D(GEOGRAPHY)
RETURNS GEOGRAPHY
AS 'SELECT ST_Force_2D($1::geometry)::GEOGRAPHY'
LANGUAGE SQL IMMUTABLE STRICT;

~ example.map

MAP
  NAME "example"

  PROJECTION
    "init=epsg:4326"   ##required
  END

  WEB
    METADATA
      "wms_title"     "gis"  ##required
      "wms_onlineresource" "http://localhost/mapserv.cgi?map=example.map&"   ##required
      "wms_srs"       "EPSG:4326 EPSG:3857"  ##recommended
      "wms_enable_request" "*"   ##necessary
    END
  END # Web

  #
  # Start of layer definitions
  #

  LAYER
    NAME "example"
    PROJECTION
      "init=epsg:4326"   ##recommended
    END
    METADATA
      "wms_title"    "Example"   ##required
    END
    STATUS OFF
    TYPE POINT
    CONNECTIONTYPE POSTGIS
    CONNECTION "host=localhost port=5432 dbname=example user=example"
    DATA "the_geog from example using srid=4326"
  END # Layer

END # Map File

~ explanation.md

Workaround from http://d.hatena.ne.jp/yellow_73/20120221

Mapserver 6.0.4, when using CONNECTIONTYPE POSTGIS with a geography column results in the following error:

msPostGISLayerWhichShapes(): Query error. Error executing query: ERROR:  function st_force_2d(geography) does not exist
LINE 1: select encode(ST_AsBinary(ST_Force_2D("the_geog"),'NDR'),'he...
                                  ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

Function ST_Force2D (also aliased as deprecated ST_Force_2D) supports only geometry parameters. After adding the st_force_2d(geography) function, mapserver no longer shows that error.