trace-cmd: Remove libtraceevent code

Now that there is an external libtraceevent repository at:

  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/

Force the use of that repository, and remove the need to have duplicate
updates.

Link: https://lore.kernel.org/linux-trace-devel/20210326165014.346445429@goodmis.org

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
27 files changed