Auto merge of #117457 - daxpedda:wasm-nontrapping-fptoint, r=wesleywiser

Stabilize Wasm target features that are in phase 4 and 5

This stabilizes the Wasm target features that are known to be working and in [phase 4 and 5](04fa8c810e).

Feature stabilized:
- [Non-trapping float-to-int conversions](https://github.com/WebAssembly/nontrapping-float-to-int-conversions)
- [Import/Export of Mutable Globals](https://github.com/WebAssembly/mutable-global)
- [Sign-extension operators](https://github.com/WebAssembly/sign-extension-ops)
- [Bulk memory operations](https://github.com/WebAssembly/bulk-memory-operations)
- [Extended Constant Expressions](https://github.com/WebAssembly/extended-const)

Features not stabilized:
- [Multi-value](https://github.com/WebAssembly/multi-value): requires rebuilding `std` #73755.
- [Reference Types](https://github.com/WebAssembly/reference-types): no point stabilizing without #103516.
- [Threads](https://github.com/webassembly/threads): requires rebuilding `std` #77839.
- [Relaxed SIMD](https://github.com/WebAssembly/relaxed-simd): separate PR #117468.
- [Multi Memory](https://github.com/WebAssembly/multi-memory): not implemented.

See https://github.com/rust-lang/rust/pull/117457#issuecomment-1787648070 for more context.

Documentation: https://github.com/rust-lang/reference/pull/1420
Tracking issue: https://github.com/rust-lang/rust/issues/44839

compiler/rustc_target/src/target_features.rs

@@ -312,14 +312,15 @@ const RISCV_ALLOWED_FEATURES: &[(&str, Stability)] = &[
 const WASM_ALLOWED_FEATURES: &[(&str, Stability)] = &[
     // tidy-alphabetical-start
     ("atomics", Unstable(sym::wasm_target_feature)),
-    ("bulk-memory", Unstable(sym::wasm_target_feature)),
+    ("bulk-memory", Stable),
     ("exception-handling", Unstable(sym::wasm_target_feature)),
+    ("extended-const", Stable),
     ("multivalue", Unstable(sym::wasm_target_feature)),
-    ("mutable-globals", Unstable(sym::wasm_target_feature)),
-    ("nontrapping-fptoint", Unstable(sym::wasm_target_feature)),
+    ("mutable-globals", Stable),
+    ("nontrapping-fptoint", Stable),
     ("reference-types", Unstable(sym::wasm_target_feature)),
     ("relaxed-simd", Unstable(sym::wasm_target_feature)),
-    ("sign-ext", Unstable(sym::wasm_target_feature)),
+    ("sign-ext", Stable),
     ("simd128", Stable),
     // tidy-alphabetical-end
 ];