The attached patch updates wabt to 1.0.34 and also disables tests on
non-x86_64 architectures.

Since the update to wabt 1.0.32 in commit
9d474e105977e46d1ffd9afe794d26882a66c7a0, tests were also enabled... but
it has failed to build architectures other than x86_64 ever since...

Because of this, diffoscope and reprotest have not been able to build,
as diffoscope has wabt in native-inputs.

Thanks to ulfvonbelow via #guix IRC for the simple suggestion of how to
disable tests!

Another option would be to selectively disable tests, though
historically there have been a number of relevent outstanding issues
related to tests on !x86_64, which might turn into a few rounds of
whack-a-mole every time wabt is updated:

  https://github.com/WebAssembly/wabt/issues/1045
  https://github.com/WebAssembly/wabt/issues/1044
  https://github.com/WebAssembly/wabt/issues/2118
  https://github.com/WebAssembly/wabt/issues/2240


live well,
  vagrant