Fix typo in irtutil.l

[Affonso-Gui]

Fixing typo in irtutil.l : segmnet-num -> segment-num .

Further reference in the file points to segment-num slot correctly.

[k-okada]

nice catch !!!!

$ touch irteus/irtutil.l ; catkin bt -vi  --make-args VERBOSE=1 | grep global

[jskeus:install] ;; irtutil.l is write protected, use temporary compile directory to /home/k-okada/catkin_ws/ws_euslisp/devel/share/euslisp/jskeus/eus/Linux64/obj/
[jskeus:install] compiling file: irtutil.l                                         
[jskeus:install] ; segment-num is assumed to be global                             
[jskeus:install] ; segment-num is assumed to be global                             
[jskeus:install] ; segment-num is assumed to be global                             
[jskeus:install] ; segment-num is assumed to be global                             
[jskeus:install] ; segment-num is assumed to be global                             
[jskeus:install] ; robot-model is assumed to be global