non-regression tool: print library version as tool version
non-regression tool: print library version as tool version

The version of the non-regression tool (obtained with option -v) is 0.1
since ages. It never changed. This change makes the -v option prints the
version of the ROHC library instead. This is more useful.

didier-barvaux/rohc,didier-barvaux/rohc,didier-barvaux/rohc,didier-barvaux/rohc,didier-barvaux/rohc