use portable-atomic for AtomicU64 where needed

AtomicU64 isn't available in libstd on all targets. portable-atomic
fills the gap, and can be nicely cfg-guarded to only be used on such
targets.

without this patch, gix-status (and thus a lot of other gix crates, and
cargo) cannot be built on Debian armel.

technically, AtomicUsize is also not guaranteed to exist for all
targets, and a similar patch could be written to support those as well
if desired.

Signed-off-by: Fabian Grünbichler <git@fabian.gruenbichler.email>

Author: Fabian-Gruenbichler

gix-status/Cargo.toml

@@ -34,6 +34,7 @@ gix-diff = { version = "^0.44.0", path = "../gix-diff", default-features = false
 thiserror = "1.0.26"
 filetime = "0.2.15"
 bstr = { version = "1.3.0", default-features = false }
+portable-atomic = "1"
 
 document-features = { version = "0.2.0", optional = true }
 

gix-status/src/index_as_worktree/function.rs

@@ -2,9 +2,15 @@ use std::{
     io,
     path::Path,
     slice::Chunks,
-    sync::atomic::{AtomicU64, AtomicUsize, Ordering},
+    sync::atomic::{AtomicUsize, Ordering},
 };
 
+#[cfg(target_has_atomic = "64")]
+use std::sync::atomic::AtomicU64;
+
+#[cfg(not(target_has_atomic = "64"))]
+use portable_atomic::AtomicU64;
+
 use bstr::BStr;
 use filetime::FileTime;
 use gix_features::parallel::{in_parallel_if, Reduce};

gix-status/src/index_as_worktree/traits.rs

@@ -52,7 +52,12 @@ pub trait ReadData<'a> {
 ///
 #[allow(clippy::empty_docs)]
 pub mod read_data {
-    use std::sync::atomic::{AtomicU64, Ordering};
+    #[cfg(target_has_atomic = "64")]
+    use std::sync::atomic::AtomicU64;
+    use std::sync::atomic::Ordering;
+
+    #[cfg(not(target_has_atomic = "64"))]
+    use portable_atomic::AtomicU64;
 
     use gix_filter::pipeline::convert::ToGitOutcome;