Fix repeated --use, --settings

Closes remarkjs/remark#1265.

Author: wooorm

lib/parse-argv.js

@@ -192,7 +192,7 @@ export function parseArgv(flags, options) {
   /** @type {Record<string, unknown>} */
   const settings = {}
   index = -1
-  if (++index < setting.length) {
+  while (++index < setting.length) {
     parseConfig(setting[index], settings)
   }
 
@@ -212,7 +212,7 @@ export function parseArgv(flags, options) {
   /** @type {PluggableMap} */
   const plugins = {}
   index = -1
-  if (++index < use.length) {
+  while (++index < use.length) {
     /** @type {Record<string, unknown>} */
     const options = {}
     const [key, value] = splitOptions(use[index])