attempt to #[allow(unnecessary_transmutes)] in neon

[bend-n]

im not sure why the #![allow] in lib.rs doesnt take effect, but for some reason it doesnt: rust-lang/rust#136083 (comment)

this might fix that? im not sure

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[Amanieu]

lib.rs is only used for the core_arch tests. The standard library includes core_arch/src/mod.rs directly.

[bend-n]

oh so i should put the #![allow] in core_arch/src/mod.rs then, right?

[Amanieu]

Yes, that would be better.

[Amanieu]

The old allow in lib.rs should be removed since it is now redundant.