remove fp16 target feature from some vreinterpret intrinsics

[usamoi]

Usage of them is accepted by clang without fullfp16 (https://godbolt.org/z/dhffa4YT9). It seems that they are missing in #1978.

cc @adamgemmell, in case I misunderstood

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[adamgemmell]

Looks good to me, thank you!

[Amanieu]

I don't believe the fp16 target feature is required on 32-bit either.

[usamoi]

This is what was done in #1978, for stores and loads.
@adamgemmell, do you have ideas?

[adamgemmell]

vreinterprets are NOPs, so there's no issues with the instruction not being available on 32 bit platforms. If it builds and the tests pass then it's fine to remove for both sets of targets

[usamoi]

fp16 is removed on arm now.

The second commit is for passing CI. rust-lang/rust#151529

[folkertdev]

For context: this includes a fix for miri failing to build std, see https://rust-lang.zulipchat.com/#narrow/channel/269128-miri/topic/Miri.20test-libstd.20Failure.20.282026-01.29/near/570520551