tools lib traceevent: Add interface for options to plugins

Add tep_plugin_add_option() and tep_plugin_print_options() to lib
traceevent library that allows plugins to have their own options. For
example, the function plugin by default does not print the parent, as it
uses the parent to do the indenting. The "parent" option is created by
the function plugin that will print the parent of the function like it
does in the trace file.

The tep_plugin_print_options() will print out the list of options that a
Cc: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
plugin has defined.

Link: http://lore.kernel.org/linux-trace-devel/20190802110101.14759-3-tz.stoyanov@gmail.com
Link: http://lore.kernel.org/linux-trace-devel/20200625100516.365338-5-tz.stoyanov@gmail.com



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: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200702185704.092654084@goodmis.org


Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>