perf test shell script: Fix test for python being disabled

"grep -cv" can exit with an error code that causes the "set -e" to abort
the script. Switch to using the grep exit code in the if condition to
avoid this.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Ross Zwisler <zwisler@chromium.org>
Cc: Shirisha G <shirisha@linux.ibm.com>
Link: https://lore.kernel.org/r/20240124043015.1388867-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: captain5050

tools/perf/tests/shell/script.sh

@@ -36,8 +36,7 @@ test_db()
 	echo "DB test"
 
 	# Check if python script is supported
-	libpython=$(perf version --build-options | grep python | grep -cv OFF)
-	if [ "${libpython}" != "1" ] ; then
+        if perf version --build-options | grep python | grep -q OFF ; then
 		echo "SKIP: python scripting is not supported"
 		err=2
 		return