Disable `sign-ext` WASM feature when building runtimes (#13804)

Co-authored-by: parity-processbot <>

substrate/utils/wasm-builder/src/wasm_project.rs

@@ -632,7 +632,7 @@ fn build_project(
 	let mut build_cmd = cargo_cmd.command();
 
 	let rustflags = format!(
-		"-C target-cpu=mvp -C link-arg=--export-table {} {}",
+		"-C target-cpu=mvp -C target-feature=-sign-ext -C link-arg=--export-table {} {}",
 		default_rustflags,
 		env::var(crate::WASM_BUILD_RUSTFLAGS_ENV).unwrap_or_default(),
 	);