transpile: hoist function-local statics to the root of the current module

[ahomescu]

Function-local statics with "uncompilable" initializers are referenced from c2rust_run_static_initializers but previously emitted inside the owner function. Hoist them to the top of the current module so c2rust_run_static_initializers can reference them by name. Example from issue #1981:

int main() {
  static const int local_static_arr[] = { 1, 2, 3 };
  static const struct foo local_static_s[] = { local_static_arr, ARR_SIZE(local_static_arr) };
  return 0;
}

Here local_static_s and local_static_arr (because the former references it) need to be moved out of main.

Fixes issue #1981.

[ahomescu]

Here is the new Rust output for the test at the top level of sections.rs:

static mut rust_local_static_arr: [::core::ffi::c_int; 3] = [
    1 as ::core::ffi::c_int,
    2 as ::core::ffi::c_int,
    3 as ::core::ffi::c_int,
];
static mut rust_local_static_s: [slice_ref; 1] = [slice_ref {
    p: ::core::ptr::null::<::core::ffi::c_int>(),
    len: 0,
}; 1];
static mut rust_chain_a: [::core::ffi::c_int; 3] = [
    5 as ::core::ffi::c_int,
    6 as ::core::ffi::c_int,
    7 as ::core::ffi::c_int,
];
static mut rust_chain_b: *mut ::core::ffi::c_int =
    unsafe { &raw const rust_chain_a as *mut ::core::ffi::c_int };
static mut rust_chain_c: *mut *mut ::core::ffi::c_int =
    ::core::ptr::null_mut::<*mut ::core::ffi::c_int>();

[fw-immunant]

Could the test here also exercise the renamer by including multiple functions with distinct, identically-named statics?

[ahomescu]

Done, the test now produces:

static mut rust_sectioned_ptr_0: uintptr_t = 0;
static mut rust_sectioned_ptr_1: uintptr_t = 0;
pub static mut rust_sectioned_ptr: uintptr_t = 0;
// ...
    rust_sectioned_ptr = NULL.expose_addr() as uintptr_t;
    rust_sectioned_ptr_0 = (&raw mut rust_section_me).expose_addr() as uintptr_t;
    rust_sectioned_ptr_1 = (&raw mut rust_section_me3).expose_addr() as uintptr_t;

[fw-immunant]

LGTM.