C2Rust generates calls to `f128` float methods without importing required traits

[rikki322]

C2Rust generates Rust code that calls floating-point methods on f128 (e.g., is_infinite, is_sign_positive) without importing the traits that provide these methods.
As a result, the generated Rust code fails to compile unless the user manually adds the required trait import.
Reproducer

#include <stdio.h>
#include <math.h>

int main(void) {
    long double huge = __builtin_huge_val();
    printf("huge_val: Input=(none), Result=%s\n",
           isinf(huge) ? "INF" : "NOT_INF");
    return 0;
}

Transpiled Rust

#![allow(
    dead_code,
    non_camel_case_types,
    non_snake_case,
    non_upper_case_globals,
    unused_assignments,
    unused_mut
)]
extern "C" {
    fn printf(__format: *const ::core::ffi::c_char, ...) -> ::core::ffi::c_int;
}
unsafe fn main_0() -> ::core::ffi::c_int {
    let mut huge: ::f128::f128 = ::f128::f128::new(::core::f64::INFINITY);
    printf(
        b"huge_val: Input=(none), Result=%s\n\0" as *const u8
            as *const ::core::ffi::c_char,
        if if huge.is_infinite() {
            if huge.is_sign_positive() { 1 } else { -1 }
        } else {
            0
        } != 0
        {
            b"INF\0" as *const u8 as *const ::core::ffi::c_char
        } else {
            b"NOT_INF\0" as *const u8 as *const ::core::ffi::c_char
        },
    );
    return 0 as ::core::ffi::c_int;
}
pub fn main() {
    unsafe { ::std::process::exit(main_0() as i32) }
}

Observed Behavior
The generated Rust code fails to compile:

error[E0599]: no method named `is_infinite` found for struct `f128`
error[E0599]: no method named `is_sign_positive` found for struct `f128`

The compiler indicates that these methods are provided by traits such as:

num_traits::float::Float

but the generated code does not import them.
Expected Behavior
C2Rust should generate the necessary trait imports when emitting calls to trait-provided floating-point methods on f128.
Environment

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