libtraceevent: Add tep_get_event() in event-parse.h

libtraceevent: Add tep_get_event() in event-parse.h

The tep_get_event() function is an official libtracevent API, described
in the library man pages. However, it cannot be used by the library users because
it is not declared in the event-parse.h file, where all libtracevent APIs are.
The function declaration is added in event-parse.h file.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190808113721.13539-1-tz.stoyanov@gmail.com
Link: http://lore.kernel.org/lkml/20190919212542.058025937@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>