Auto merge of #13986 - iamrohit7:tidy-feature-attrs, r=Wafflespeanut

Make test-tidy check for alphabetical ordering of #![feature(...)] statements

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [x] These changes fix #13954  (github issue number if applicable).

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- [X] There are tests for these changes OR
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components/net/lib.rs

@@ -2,9 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#![feature(box_syntax)]
 #![feature(custom_attribute)]
 #![feature(custom_derive)]
-#![feature(box_syntax)]
 #![feature(fnbox)]
 #![feature(mpsc_select)]
 #![feature(plugin)]