servo: Merge #18247 - Silenced camel case warning for the iOS enum variant (from Majora320:master); r=emilio

Fix a simple warning.
---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

This change is obviously too trivial for tests.

Source-Repo: https://github.com/servo/servo
Source-Revision: 04fb310847c55ba70c27e7badcfb6b04c2e50d63

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : c148e8ea68a1583155e0055578e6862182557d1c

servo/components/config/opts.rs

@@ -448,6 +448,7 @@ pub fn multiprocess() -> bool {
 enum UserAgent {
     Desktop,
     Android,
+    #[allow(non_camel_case_types)]
     iOS
 }