Auto merge of #18189 - JJayet:ios_support, r=larsbergstrom

First step toward iOS Support

This mostly prevents Gaol/sandboxing to be used during compilation.
There are a number of issues with : `expat-sys`, `servo-freetype-sys`, `fontsan`, `heartbeats-simple-sys`, `mozjs_sys`.

Also modified `components/script/dom/navigatorinfo.rs` in order to add iOS.

```rust
#[cfg(target_os = "ios")]
pub fn Platform() -> DOMString {
    DOMString::from("iOS")
}
```

See here for more informations : https://github.com/servo/servo/issues/18154

---

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes partially work on #18154

- [X] These changes do not require tests because it deals with the compile toolchain

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components/script/dom/navigatorinfo.rs

@@ -36,6 +36,11 @@ pub fn Platform() -> DOMString {
     DOMString::from("Mac")
 }
 
+#[cfg(target_os = "ios")]
+pub fn Platform() -> DOMString {
+    DOMString::from("iOS")
+}
+
 pub fn UserAgent() -> DOMString {
     DOMString::from(&*opts::get().user_agent)
 }