bench: refactor to use dynamic memory allocation in blas/base/snrm2

PR-URL: #8818
Ref: #8643
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: opbot-xd

lib/node_modules/@stdlib/blas/base/snrm2/benchmark/c/benchmark.length.c

@@ -96,11 +96,12 @@ static float rand_float( void ) {
 */
 static double benchmark1( int iterations, int len ) {
 	double elapsed;
-	float x[ len ];
+	float *x;
 	float z;
 	double t;
 	int i;
 
+	x = (float *)malloc( len * sizeof( float ) );
 	for ( i = 0; i < len; i++ ) {
 		x[ i ] = ( rand_float() * 20000.0f ) - 10000.0f;
 	}
@@ -117,6 +118,7 @@ static double benchmark1( int iterations, int len ) {
 	if ( z != z ) {
 		printf( "should not return NaN\n" );
 	}
+	free( x );
 	return elapsed;
 }
 
@@ -129,11 +131,12 @@ static double benchmark1( int iterations, int len ) {
 */
 static double benchmark2( int iterations, int len ) {
 	double elapsed;
-	float x[ len ];
+	float *x;
 	float z;
 	double t;
 	int i;
 
+	x = (float *)malloc( len * sizeof( float ) );
 	for ( i = 0; i < len; i++ ) {
 		x[ i ] = ( rand_float() * 20000.0f ) - 10000.0f;
 	}
@@ -150,6 +153,7 @@ static double benchmark2( int iterations, int len ) {
 	if ( z != z ) {
 		printf( "should not return NaN\n" );
 	}
+	free( x );
 	return elapsed;
 }