Rollup merge of #137094 - RalfJung:softfloat-means-no-simd, r=tgross35

x86_win64 ABI: do not use xmm0 with softfloat ABI

This adjusts rust-lang/rust#134290 to not apply the new logic to targets marked as "softfloat". That fixes most instances of the issue brought up [here](rust-lang/rust#116558 (comment)).

r? `@tgross35`

Author: matthiaskrgr