tools lib traceevent: traceevent API cleanup

tools lib traceevent: traceevent API cleanup

In order to make libtraceevent into a proper library, its API should be
straightforward. This patch hides few API functions, intended for
internal usage only:

tep_free_event(), tep_free_format_field(), __tep_data2host2(),
__tep_data2host4() and __tep_data2host8().
The patch also alignes the libtraceevent summary man page with
these API changes.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20181130154647.891651290@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>