wasmparser: fix crate feature propagation

[Robbepop]

No longer enable indexmap and hashbrown when std feature is enabled without hash-collections feature.

[Robbepop]

The fuzz job fails with

error: toolchain 'nightly-x86_64-unknown-linux-gnu' does not support target 'wasm32-wasi'; did you mean 'wasm32-wasip1'?

Seems to be unrelated to this PR.

[alexcrichton]

Thanks! Mind rebasing to pick up the fix from #1901?

[Robbepop]

Thanks! Mind rebasing to pick up the fix from #1901?

Done :)

[Robbepop]

@alexcrichton It seems wasm-metadata strictly requires the hash-collections crate feature from the wasmparser crate. I had to enable it to make wasm-metadata compile again.