* A new format is required to generate definitions for ust tracepoints.
Files ust_events_h.py and ust_events_c.py define common macros, while
new function ust_events_h in events.py does the actual definition of
each tracepoint.
* ust.py generates the new interface for calling userspace tracepoints
with LTTng 2.x, replacing trace_name(args) to tracepoint(name, args).
* As explained in ust_events_c.py, -Wredundant-decls gives a warning
when compiling with gcc 4.7 or older. This is specific to lttng-ust so
for now use a pragma clause to avoid getting a warning.