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

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: na
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: na
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: missing_dependencies
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: passed
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

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;
 }