bench: fix value types

Signed-off-by: Athan <kgryte@gmail.com>

Author: kgryte

lib/node_modules/@stdlib/blas/ext/base/sindex-of-row/benchmark/c/benchmark.length.c

@@ -60,7 +60,7 @@ static void print_summary( int total, int passing ) {
 * @param elapsed      elapsed time in seconds
 */
 static void print_results( int iterations, float elapsed ) {
-	float rate = (float)iterations / elapsed;
+	double rate = (double)iterations / elapsed;
 	printf( "  ---\n" );
 	printf( "  iterations: %d\n", iterations );
 	printf( "  elapsed: %0.9f\n", elapsed );