Incorrect translation of `long double` → `bool` causes Rust type mismatch

[lynae99]

When translating a cast from long double to bool, the transpiler generates a comparison against an untyped floating-point literal (0.).
However, the long double value is translated to ::f128::f128, which results in a type mismatch (f128 vs default float literal) and causes the generated Rust code to fail compilation.
Reproducer

#include <stdbool.h>

int main(void) {
    long double ld_zero = 0.0L;
    long double ld_non_zero = 0.1L;

    bool ld_zero_as_bool = (bool)ld_zero;
    bool ld_non_zero_as_bool = (bool)ld_non_zero;
}

Generated Rust

#![allow(
    dead_code,
    non_camel_case_types,
    non_snake_case,
    non_upper_case_globals,
    unused_assignments,
    unused_mut
)]
unsafe fn main_0() -> ::core::ffi::c_int {
    let mut ld_zero: ::f128::f128 = ::f128::f128::new(0.0);
    let mut ld_non_zero: ::f128::f128 = ::f128::f128::new(0.1);
    let mut ld_zero_as_bool: bool = ld_zero != 0.;
    let mut ld_non_zero_as_bool: bool = ld_non_zero != 0.;
    return 0;
}
pub fn main() {
    unsafe { ::std::process::exit(main_0() as i32) }
}

Observed Behavior
The generated Rust code fails to compile:

error[E0308]: mismatched types
  --> src/main.rs:12:48
   |
12 |     let mut ld_zero_as_bool: bool = ld_zero != 0.;
   |                                                ^^ expected struct `f128`, found floating-point number

error[E0308]: mismatched types
  --> src/main.rs:13:56
   |
13 |     let mut ld_non_zero_as_bool: bool = ld_non_zero != 0.;
   |                                                        ^^ expected struct `f128`, found floating-point number

Environment

• c2rust version: v0.21.0
• platform: Ubuntu 24.04
• Rust: nightly-2022-08-08
• Clang version: 17.0.6