Use rustc's APFloat impl instead of interpreter host floats
Use rustc's APFloat impl instead of interpreter host floats

aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,rust-lang/miri,aidancully/rust,tsion/miri,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,rust-lang/miri,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,graydon/rust,rust-lang/miri,aidancully/rust,rust-lang/miri