chore: update bench.c to handle NaN elements

Author: Neerajpathak07

lib/node_modules/@stdlib/stats/base/dsnanmeanors/benchmark/c/benchmark.length.c

@@ -102,7 +102,11 @@ static double benchmark1( int iterations, int len ) {
 	int i;
 
 	for ( i = 0; i < len; i++ ) {
-		x[ i ] = ( rand_float()*20000.0f ) - 10000.0f;
+		if ( rand_float() < 0.2f ) {
+			x[ i ] = 0.0f / 0.0f; // NaN
+		} else {
+			x[ i ] = ( rand_float()*20000.0f ) - 10000.0f;
+		}
 	}
 	v = 0.0;
 	t = tic();
@@ -136,7 +140,11 @@ static double benchmark2( int iterations, int len ) {
 	int i;
 
 	for ( i = 0; i < len; i++ ) {
-		x[ i ] = ( rand_float()*20000.0f ) - 10000.0f;
+		if ( rand_float() < 0.2f ) {
+			x[ i ] = 0.0f / 0.0f; // NaN
+		} else {
+			x[ i ] = ( rand_float()*20000.0f ) - 10000.0f;
+		}
 	}
 	v = 0.0;
 	t = tic();