perf tools: Don't install libtraceevent plugins as its not anymore in the kernel...

perf tools: Don't install libtraceevent plugins as its not anymore in the kernel sources

While doing 'make -C tools/perf build-test' one can notice error
messages while trying to install libtraceevent plugins, stop doing that
as libtraceevent isn't anymore a homie.

These are the warnings dealt with:

   make_install_prefix_slash_O: make install prefix=/tmp/krava/
    failed to find: /tmp/krava/etc/bash_completion.d/perf
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_cfg80211.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_scsi.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_xen.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_function.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_sched_switch.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_mac80211.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_kvm.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_kmem.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_hrtimer.so
    failed to find: /tmp/krava/lib64/traceevent/plugins/plugin_jbd2.so

Fixes: 4171925aa9f3f7bf ("tools lib traceevent: Remove libtraceevent")
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lore.kernel.org/lkml/Y7xXz+TSpiCbQGjw@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>