string.h: don't pollute the namespace with locale.h

Previously, we included all of `<locale.h>` in order to get `locale_t`.
This commit separates it into a `<bits/locale-t.h>` header (generated by
cbindgen) to better deal with this.

src/header/bits_locale-t/cbindgen.toml

@@ -0,0 +1,14 @@
+sys_includes = []
+include_guard = "_RELIBC_BITS_LOCALE_T_H"
+language = "C"
+style = "type"
+no_includes = true
+cpp_compat = true
+
+[export]
+include = [
+  "locale_t"
+]
+
+[enum]
+prefix_with_name = true

src/header/bits_locale-t/mod.rs

@@ -0,0 +1 @@
+pub type locale_t = *mut core::ffi::c_void;

src/header/locale/cbindgen.toml

@@ -1,4 +1,7 @@
 include_guard = "_RELIBC_LOCALE_H"
+after_includes = """
+#include <bits/locale-t.h> // for locale_t
+"""
 trailer = "#include <bits/locale.h>"
 language = "C"
 style = "Tag"

src/header/locale/mod.rs

@@ -27,7 +27,7 @@ use constants::*;
 mod data;
 use data::*;
 
-pub type locale_t = *mut c_void;
+use super::bits_locale_t::locale_t;
 /// constant struct to "C" or "POSIX" locale
 /// mutable because POSIX demands a mutable pointer
 static mut POSIX_LOCALE: lconv = posix_lconv();

src/header/mod.rs

@@ -4,6 +4,8 @@ pub mod _aio;
 pub mod _fenv;
 pub mod arpa_inet;
 pub mod assert;
+#[path = "bits_locale-t/mod.rs"]
+pub mod bits_locale_t;
 pub mod bits_pthread;
 pub mod bits_sched;
 // complex.h implemented in C

src/header/string/cbindgen.toml

@@ -1,5 +1,8 @@
-sys_includes = ["stddef.h", "stdint.h", "strings.h", "locale.h"]
+sys_includes = ["stddef.h", "stdint.h", "strings.h"]
 include_guard = "_RELIBC_STRING_H"
+after_includes = """
+#include <bits/locale-t.h> // for locale_t
+"""
 language = "C"
 style = "Tag"
 no_includes = true

src/header/string/mod.rs

@@ -20,7 +20,7 @@ use crate::{
     raw_cell::RawCell,
 };
 
-use super::locale::{THREAD_LOCALE, locale_t};
+use super::{bits_locale_t::locale_t, locale::THREAD_LOCALE};
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/memccpy.html>.
 ///