Tracepoint probes don't need extern C

tracepoint.h has the proper extern C guards, so every liblttng-ust API
called from the probe has the proper linkage.

The rest of the symbols are only meaningful within the probe, so we
don't care if they are mangled or not.

This fixes the two examples, and lttng-gen-tp.

Fixes #597

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
examples: tracepoint probes don't need extern C

Fix all UST demo applications under doc/examples/

Fixes #597

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Specialize lttng_ust_lib_ring_buffer_client_cb

Prepare the ring-buffer config to have custom callbacks. These custom
callbacks are not related to the ring-buffer operations but allow
applications to add custom functions.
No additional feature or change in behaviour in this patch.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
LTTng ringbuffer ABI calls for index generation

These new calls export the data required for the consumer to
generate the index while tracing :
- timestamp begin
- timestamp end
- events discarded
- context size
- packet size
- stream id

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>