As per bytecodealliance/rfcs#10, the first step in our transition to the
new Cranelift x86-64 backend by default in Wasmtime is to switch our
fuzzers and monitor for any breakage.
This PR moves all Wasmtime fuzz targets over to use the new backend. The
differential old-vs-new-backend target still works by dynamically
selecting both backends (the build feature just changes the default,
which is what all the other fuzz targets use).
We should watch for ~a week or so, I think, on oss-fuzz, to make sure
this sticks without issue before moving further.

In bytecodealliance/rfcs#10, we have outlined a process by which we're
switching to a new compiler backend by default. The first step in this
process is to switch our fuzzing targets to use the new backend and wait
for any issues.
This PR adds the Cargo feature that enables the new backend in all
fuzzing targets.

In bytecodealliance/rfcs#10, we have outlined a process by which we're
switching to a new compiler backend by default. The first step in this
process is to switch our fuzzing targets to use the new backend and wait
for any issues.
This PR adds the Cargo feature that enables the new backend in all
fuzzing targets.