If LIBTRACEEVENT_DYNAMIC is enabled then avoid the install step for
the plugins. If disabled correct DESTDIR so that the plugins are
installed under <lib>/traceevent/plugins.

Fixes: ef019df0 ("perf build: Install libtraceevent locally when building")
Reported-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20221205225940.3079667-2-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>