Remove all-arch from cranelift-interpreter (#3872)

I frequently notice that the fuzz build of `cranelift-codegen` takes an
extremely long time and recently realized that one issue is that when
fuzzers are built we enable all of the backends in `cranelift-codegen`
but AFAIK only the native backend is actually fuzzed. I traced the
inclusion of `all-arch` back to #2323, specifically [this comment][1]
and it looks like now that the old backend is removed this should be
able to be removed as well.

[1]: https://github.com/bytecodealliance/wasmtime/pull/2323#discussion_r515228552

cranelift/interpreter/Cargo.toml

@@ -11,7 +11,7 @@ readme = "README.md"
 edition = "2018"
 
 [dependencies]
-cranelift-codegen = { path = "../codegen", version = "0.81.0", features = ["all-arch"] }
+cranelift-codegen = { path = "../codegen", version = "0.81.0" }
 cranelift-entity = { path = "../entity", version = "0.81.0" }
 log = { version = "0.4.8", default-features = false }
 smallvec = "1.6.1"