trace-cmd: Add event-plugin.o to Makefile
trace-cmd: Add event-plugin.o to Makefile

The even-plugin.o is the tools/lib/traceevent file used for plugins.
We need to convert it to be usable for trace-cmd too. Work to add more
features to the file, but we need to compile it first.

Signed-off-by: Steven Rostedt <43232e92d70cc7aa53504ad0397085ee47bad87f@goodmis.org>

bigzz/trace-cmd,bigzz/trace-cmd