clif: Don't set the compiler-builtins-no-f16-f128 feature

Since rust-lang/rust be35d37d8b ("Use the compiler to determine
whether or not to enable f16 and f128"), `compiler-builtins` relies on
`rustc` to report whether or not `f16` and `f128` are supported, which
is reported by the backend. This means that there should no longer be
any need to unconditionally disable the types for clif in Bootstrap.

Backend config: a955f1cd09/compiler/rustc_codegen_cranelift/src/lib.rs (L224-L233)

src/bootstrap/src/core/build_steps/compile.rs

@@ -597,11 +597,6 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
     let mut features = String::new();
 
-    if stage != 0 && builder.config.default_codegen_backend(target).as_deref() == Some("cranelift")
-    {
-        features += "compiler-builtins-no-f16-f128 ";
-    }
-
     if builder.no_std(target) == Some(true) {
         features += " compiler-builtins-mem";
         if !target.starts_with("bpf") {