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

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
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    status: passed
  - task: lint_editorconfig
    status: passed
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    status: na
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    status: na
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    status: na
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    status: na
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    status: missing_dependencies
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    status: na
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    status: passed
---

Author: Faraz Ghani

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

@@ -96,11 +96,14 @@ static double rand_double( void ) {
 */
 static double benchmark1( int iterations, int len ) {
 	double elapsed;
-	double x[ len ];
-	double y[ len ];
+	double *x;
+	double *y;
 	double t;
 	int i;
 
+	x = (double *) malloc( len * sizeof( double ) );
+	y = (double *) malloc( len * sizeof( double ) );
+
 	for ( i = 0; i < len; i++ ) {
 		x[ i ] = ( rand_double()*20000.0 ) - 10000.0;
 		y[ i ] = 0.0;
@@ -117,6 +120,9 @@ static double benchmark1( int iterations, int len ) {
 	if ( y[ 0 ] != y[ 0 ] ) {
 		printf( "should not return NaN\n" );
 	}
+
+	free( x );
+	free( y );
 	return elapsed;
 }
 
@@ -129,11 +135,13 @@ static double benchmark1( int iterations, int len ) {
 */
 static double benchmark2( int iterations, int len ) {
 	double elapsed;
-	double x[ len ];
-	double y[ len ];
+	double *x;
+	double *y;
 	double t;
 	int i;
 
+	x = (double *) malloc( len * sizeof( double ) );
+	y = (double *) malloc( len * sizeof( double ) );
 	for ( i = 0; i < len; i++ ) {
 		x[ i ] = ( rand_double()*20000.0 ) - 10000.0;
 		y[ i ] = 0.0;
@@ -150,6 +158,8 @@ static double benchmark2( int iterations, int len ) {
 	if ( y[ 0 ] != y[ 0 ] ) {
 		printf( "should not return NaN\n" );
 	}
+	free( x );
+	free( y );
 	return elapsed;
 }