bench: avoid calling PRNG within loop

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

Author: kgryte

lib/node_modules/@stdlib/assert/contains/benchmark/benchmark.length.js

@@ -23,7 +23,6 @@
 var bench = require( '@stdlib/bench' );
 var isBoolean = require( '@stdlib/assert/is-boolean' ).isPrimitive;
 var pow = require( '@stdlib/math/base/special/pow' );
-var randu = require( '@stdlib/random/base/randu' );
 var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var contains = require( './../lib' );
@@ -62,7 +61,7 @@ function createBenchmark( fcn, len ) {
 		b.tic();
 		for ( i = 0; i < b.iterations; i++ ) {
 			// Note: we are testing the worst case scenario where a function must scan the entire array before finding a value.
-			x[ len-2 ] = randu();
+			x[ len-2 ] -= 1;
 			bool = fcn( x, len-1 );
 			if ( typeof bool !== 'boolean' ) {
 				b.fail( 'should return a boolean' );