perf bench: Avoid NDEBUG warning

With NDEBUG set the asserts are compiled out. This yields
"unused-but-set-variable" variables. Move these variables behind
NDEBUG to avoid the warning.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: 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: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230330183827.1412303-1-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/bench/find-bit-bench.c

@@ -61,7 +61,6 @@ static int do_for_each_set_bit(unsigned int num_bits)
 	double time_average, time_stddev;
 	unsigned int bit, i, j;
 	unsigned int set_bits, skip;
-	unsigned int old;
 
 	init_stats(&fb_time_stats);
 	init_stats(&tb_time_stats);
@@ -73,7 +72,10 @@ static int do_for_each_set_bit(unsigned int num_bits)
 			__set_bit(i, to_test);
 
 		for (i = 0; i < outer_iterations; i++) {
-			old = accumulator;
+#ifndef NDEBUG
+			unsigned int old = accumulator;
+#endif
+
 			gettimeofday(&start, NULL);
 			for (j = 0; j < inner_iterations; j++) {
 				for_each_set_bit(bit, to_test, num_bits)
@@ -85,7 +87,9 @@ static int do_for_each_set_bit(unsigned int num_bits)
 			runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
 			update_stats(&fb_time_stats, runtime_us);
 
+#ifndef NDEBUG
 			old = accumulator;
+#endif
 			gettimeofday(&start, NULL);
 			for (j = 0; j < inner_iterations; j++) {
 				for (bit = 0; bit < num_bits; bit++) {