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

---
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: sujalcharati

lib/node_modules/@stdlib/blas/ext/base/cfill/benchmark/c/benchmark.length.c

@@ -97,11 +97,13 @@ static float rand_float( void ) {
 */
 static double benchmark1( int iterations, int len ) {
 	stdlib_complex64_t alpha;
-	float x[ len*2 ];
+	float *x;
 	double elapsed;
 	double t;
 	int i;
 
+	x = (float *) malloc( len * 2 * sizeof(float) );
+
 	alpha = stdlib_complex64( 1.0f, 0.0f );
 	for ( i = 0; i < len*2; i += 2 ) {
 		x[ i ] = ( rand_float()*2.0f ) - 1.0f;
@@ -120,6 +122,8 @@ static double benchmark1( int iterations, int len ) {
 	if ( x[ 0 ] != x[ 0 ] ) {
 		printf( "should not return NaN\n" );
 	}
+
+	free( x );
 	return elapsed;
 }
 
@@ -132,11 +136,11 @@ static double benchmark1( int iterations, int len ) {
 */
 static double benchmark2( int iterations, int len ) {
 	stdlib_complex64_t alpha;
-	float x[ len*2 ];
+	float *x;
 	double elapsed;
 	double t;
 	int i;
-
+	x = (float *) malloc( len * 2 * sizeof(float) );
 	alpha = stdlib_complex64( 1.0f, 0.0f );
 	for ( i = 0; i < len*2; i += 2 ) {
 		x[ i ] = ( rand_float()*2.0f ) - 1.0f;
@@ -155,6 +159,8 @@ static double benchmark2( int iterations, int len ) {
 	if ( x[ 0 ] != x[ 0 ] ) {
 		printf( "should not return NaN\n" );
 	}
+
+	free( x );
 	return elapsed;
 }