Replace AtomicU64 with AtomicUsize

[dm0-]

PowerPC and MIPS do not have AtomicU64, but AtomicUsize is a more portable type that can be used as a replacement: https://doc.rust-lang.org/std/sync/atomic/index.html#portability

I hit this build failure while trying to cross-compile Firefox for PowerPC. It could use AtomicU32 and .into() instead, but the size type will keep a 64-bit value where supported.

[kvark]

CI doesn't like it?

[dm0-]

It appears unrelated.

   Compiling webrender_api v0.61.0 (/home/worker/webrender/webrender_api)
     Running `rustc --crate-name webrender_api --edition=2018 webrender_api/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C panic=abort -C debuginfo=2 -C metadata=64f5ddcdecb59520 -C extra-filename=-64f5ddcdecb59520 --out-dir /home/worker/webrender/target/debug/deps -C incremental=/home/worker/webrender/target/debug/incremental -L dependency=/home/worker/webrender/target/debug/deps --extern app_units=/home/worker/webrender/target/debug/deps/libapp_units-736bdab8669efab7.rmeta --extern bitflags=/home/worker/webrender/target/debug/deps/libbitflags-d72e041c687a4189.rmeta --extern byteorder=/home/worker/webrender/target/debug/deps/libbyteorder-c4bff97c67af76a7.rmeta --extern derive_more=/home/worker/webrender/target/debug/deps/libderive_more-733787eda813cf26.so --extern euclid=/home/worker/webrender/target/debug/deps/libeuclid-59d60877d86e5835.rmeta --extern malloc_size_of_derive=/home/worker/webrender/target/debug/deps/libmalloc_size_of_derive-b17d029157d9743b.so --extern peek_poke=/home/worker/webrender/target/debug/deps/libpeek_poke-11c33769db5d6d8b.rmeta --extern serde=/home/worker/webrender/target/debug/deps/libserde-33b54a58df4df7ca.rmeta --extern serde_bytes=/home/worker/webrender/target/debug/deps/libserde_bytes-b2634c1a8d927eab.rmeta --extern serde_derive=/home/worker/webrender/target/debug/deps/libserde_derive-ad2119ab057cd555.so --extern time=/home/worker/webrender/target/debug/deps/libtime-f3f3af9bda2e2c10.rmeta --extern malloc_size_of=/home/worker/webrender/target/debug/deps/libwr_malloc_size_of-0effc33b58526305.rmeta --deny warnings`
error: use of deprecated item 'std::error::Error::description': use the Display impl or to_string()
  --> webrender_api/src/channel.rs:83:71
   |
83 |         self.rx.recv().map_err(|e| io::Error::new(ErrorKind::Other, e.description()))
   |                                                                       ^^^^^^^^^^^
   |
   = note: `-D deprecated` implied by `-D warnings`
error: aborting due to previous error
error: could not compile `webrender_api`.

[staktrace]

If you rebase your PR on the latest master that error should go away. (It was fixed in bug 1622256 which got merged in #3883)

[dm0-]

Thanks, that CI build seems to succeed now.

[kvark]

Created https://bugzilla.mozilla.org/show_bug.cgi?id=1623407, will port the PR shortly.