Ensure EH does not change code after linking (#12493)

We used to require Binaryen postprocessing for EH and have a `fail`
requirement for it in `other.test_immutable_after_link`. I deleted the
requirement in #12399, but it could have been better if I didn't just
delete it but changed it to an `ok` requirement. This PR adds that.

Author: aheejin

tests/test_other.py

@@ -9009,6 +9009,8 @@ def ok(args, filename='hello_world.cpp', expected='hello, world!'):
     ok(required_flags, filename='hello_world_main_loop.cpp')
     # -O1 is ok as we don't run wasm-opt there (but no higher, see below)
     ok(required_flags + ['-O1'])
+    # Exception support shouldn't require changes after linking
+    ok(required_flags + ['-fexceptions'])
 
     # other builds fail with a standard message + extra details
     def fail(args, details):