perf test shell diff: Skip test if test_loop symbol is missing in the perf binary

The diff test depends on finding the symbol test_loop in perf and will
fail if perf has been stripped and no debug object is available. In that
case, skip the test instead.
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231205164924.835682-1-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/diff.sh

@@ -9,8 +9,15 @@ perfdata1=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
 perfdata2=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
 perfdata3=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
 testprog="perf test -w thloop"
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/perf_has_symbol.sh
+. "${shelldir}"/lib/perf_has_symbol.sh
+
 testsym="test_loop"
 
+skip_test_missing_symbol ${testsym}
+
 cleanup() {
   rm -rf "${perfdata1}"
   rm -rf "${perfdata1}".old