GenericValue: ptr return 0 if we have an invalid type
GenericValue: ptr return 0 if we have an invalid type

Change-Id: Iacb0ea49622fa82f141165637e2fff9add54bb90
Reviewed-on: http://gerrit.aldebaran.lan:8080/18584
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>

aldebaran/libqi,bsautron/libqi,aldebaran/libqi,aldebaran/libqi,vbarbaresi/libqi