Having a verbose option will allow shell tests to provide extra failure
details when the fail or skip.

Committer notes:

Keep the 'script' variable at PATH_MAX, as its just something we'll pass
to system(), not really a "path", so being arbitrary, reduce the patch
size by not adding the three extra bytes to the 'script' variable.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210621215648.2991319-1-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>