LTTng

Following discussion with David Goulet who is currently instrumenting the tor project with lttng-ust, it appears that the following use-case should be documented more clearly in the web documentation:

• Instrumentation of applications with LTTng-UST

A tracepoint provider header should be included once per application within a compile unit after a #define CREATE_TRACE_POINTS.

It can be included multiple times throughout other compile units of the applications, but make sure the CREATE_TRACE_POINTS macro is not defined before those include, otherwise LTTng-UST will complain about multiple tracepoint probe definitions.