tracepoint: split provider and event name

tracepoint: split provider and event name

Now that we bump the ABI, it's a good opportunity to split the
tracepoint "name" field, which is a concatenation of

  #provider_name ':' #event_name

into separate provider and name fields.

Reject tracepoints and callsites which are larger than the maximum
length supported by LTTng-UST rather than silently truncating them.
This emits a warning visible with LTTNG_UST_DEBUG=1 to allow pinpointing
erroneous users.

Note that as long as tracepoints are defined statically with the
tracepoint API, the length of the provider and event names is validated
with a build-time check.

This means the core of tracepoint.c is now agnostic to the length of the
tracepoint provider/event name. If there is ever a change to the
LTTng-UST protocol allowing larger length for those, changing the
length validations will be straightforward.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I770cf57e1f19ec6f4d8c1c7b05e537a176a046cb