build!: declare extern blocks as unsafe to comply with Rust 2024

Signed-off-by: Esteve Fernandez <esteve@apache.org>

Author: esteve

rosidl_runtime_rs/src/sequence.rs

@@ -503,7 +503,7 @@ impl std::error::Error for SequenceExceedsBoundsError {}
 macro_rules! impl_sequence_alloc_for_primitive_type {
     ($rust_type:ty, $init_func:ident, $fini_func:ident, $copy_func:ident) => {
         #[link(name = "rosidl_runtime_c")]
-        extern "C" {
+        unsafe extern "C" {
             fn $init_func(seq: *mut Sequence<$rust_type>, size: usize) -> bool;
             fn $fini_func(seq: *mut Sequence<$rust_type>);
             fn $copy_func(

rosidl_runtime_rs/src/string.rs

@@ -116,7 +116,7 @@ pub struct StringExceedsBoundsError {
 macro_rules! string_impl {
     ($string:ty, $char_type:ty, $unsigned_char_type:ty, $string_conversion_func:ident, $init:ident, $fini:ident, $assignn:ident, $sequence_init:ident, $sequence_fini:ident, $sequence_copy:ident) => {
         #[link(name = "rosidl_runtime_c")]
-        extern "C" {
+        unsafe extern "C" {
             fn $init(s: *mut $string) -> bool;
             fn $fini(s: *mut $string);
             fn $assignn(s: *mut $string, value: *const $char_type, n: usize) -> bool;