Fix build of adder wasm (#54)

polkadot/test-parachains/adder/wasm/src/lib.rs

@@ -19,7 +19,7 @@
 #![no_std]
 
 #![feature(
-	alloc, core_intrinsics, lang_items, panic_implementation, core_panic_info,
+	alloc, core_intrinsics, lang_items, panic_handler, core_panic_info,
 	alloc_error_handler
 )]
 
@@ -39,7 +39,7 @@ use parachain::ValidationResult;
 use parachain::codec::{Encode, Decode};
 use adder::{HeadData, BlockData};
 
-#[panic_implementation]
+#[panic_handler]
 #[no_mangle]
 pub fn panic(_info: &panic::PanicInfo) -> ! {
 	unsafe {