rustc_middle: `ImmTy`'s `Display` implementation adds a weird-looking suffix to special floating point values.

[eduardosm]

When printing an ImmTy that contains an special floating point value such as infinity or NaN, it will add an f32 or f64 suffix, making it look like Inff32 or NaNf32, which does not look very pretty.

First observed in rust-lang/miri#3185 (comment).

[RalfJung]

This should probably be Inf_f32 or so instead.

The code for that is here:

rust/compiler/rustc_middle/src/ty/print/pretty.rs

Lines 1479 to 1484 in 15f2156

	ty::Float(ty::FloatTy::F32) => {
	p!(write("{}f32", Single::try_from(int).unwrap()))
	}
	ty::Float(ty::FloatTy::F64) => {
	p!(write("{}f64", Double::try_from(int).unwrap()))
	}