[bug-recutils] The SEX operators <= and >= don't work

[Mampir]

The manual describes of these SEX operator, but the utilities can't
work with them.

An example:

  # -*- mode: rec -*-
  
  %rec: Tool
  %type: Id int
  
  Id: 0
  Name: Pliers
  
  Id: 1
  Name: Adze
  
  Id: 2
  Name: Hammer drill
  
  # End of tools.rec

Commands:

  $ recsel -t Tool -e "Id >= 1" tools.rec
  recsel: error: invalid selection expression.
  $ recsel -t Tool -e "Id <= 1" tools.rec
  recsel: error: invalid selection expression.