Bump soname major to 1

Bump soname major to 1

The event notifier (trigger) feature required a significant rework of
public data structures which should never have been made public in the
first place.

Bump the soname major to 1, which will require applications and
tracepoint providers to rebuild against an updated lttng-ust to use it.

Old applications and tracepoint providers linked against libraries with
major soname 0 should be able to co-exist on the same system.

Now (before the next release) is a good time to eliminate LTTng-UST APIs
which were made public by accident.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I804c875ab7c0ae30daaab4817614574ccebc26c8