Ignore an i128 test on emscripten

Author: alexcrichton

src/test/run-pass/issue-38763.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// ignore-emscripten
+
 #![feature(i128_type)]
 
 #[repr(C)]