[fix]: resolved C linting error

Author: Shivam-1827

lib/node_modules/@stdlib/math/base/special/roundn/src/addon.c

@@ -16,7 +16,26 @@
 * limitations under the License.
 */
 
+#include <node_api.h>
+#include <math.h>
 #include "stdlib/math/base/special/roundn.h"
 #include "stdlib/math/base/napi/binary.h"
 
+double stdlib_base_roundn(double x, int n) {
+    double factor = pow(10, n);
+    return round(x / factor) * factor;
+}
+
+NAPI_MODULE_INIT() {
+    napi_value fn;
+    napi_status status = napi_create_function(env, NULL, 0, stdlib_base_roundn, NULL, &fn);
+    if (status != napi_ok) {
+        napi_throw_error(env, NULL, "Unable to create function");
+        return NULL;
+    }
+
+    return fn;
+}
+
+
 STDLIB_MATH_BASE_NAPI_MODULE_DI_D(stdlib_base_roundn)