Convert strtold to Rust

src/header/stdlib/cbindgen.toml

@@ -6,5 +6,8 @@ style = "Type"
 no_includes = true
 cpp_compat = true
 
+[export.rename]
+"c_longdouble" = "long double"
+
 [enum]
 prefix_with_name = true

src/header/stdlib/mod.rs

@@ -1479,7 +1479,11 @@ pub unsafe extern "C" fn strtol(s: *const c_char, endptr: *mut *mut c_char, base
     )
 }
 
-// TODO: strtold(), when long double is available
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strtold.html>.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn strtold(s: *const c_char, endptr: *mut *mut c_char) -> c_longdouble {
+    strto_float_impl!(c_longdouble, s, endptr)
+}
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strtol.html>.
 #[unsafe(no_mangle)]