Current LIBVERSION is 1:1:1 (current:revision:age), so major=current-age
makes it be major=0: libgtpnl0.
It can bee seen in current osmocom debian repos that libgtpnl1 package
contains libgtpnl.so.0.
Let's set package name accordingly.
Change-Id: I7d2fa50b6a17a598467f555558660ef2396c1744