perf tools: Remove trim() implementation, use tools/lib's strim()

Moving more stuff out of tools/perf/util/ and using the kernel idiom.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-wpj8rktj62yse5dq6ckny6de@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>