Description
Currently wgpu-core/src/device/resource.rs uses AtomicU64. This prevents successful compilation and use of Ruffle on it.
I wanted to make sure this is known and see if there was some simple workaround for it so I can use it on PowerPC 32-bit and MIPS.

Repro steps
I tried to build ruffle with cargo build --target=powerpc-unknown-linux-gnu

Expected vs observed behavior

error[E0432]: unresolved import `std::sync::atomic::AtomicU64`
  --> /path/to/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wgpu-core
56 |         atomic::{AtomicBool, AtomicU64, Ordering},
   |                              ^^^^^^^^^
   |                              |
   |                              no `AtomicU64` in `sync::atomic`

This is not the sole blocker for building ruffle, but it is the first I come across (the second is ring).

Platform
Build host is amd64 debian Linux, i5-3470 with 16GB RAM, not that I think it matters for this.
I am not using debian's rust packages; I am using the generic ones from https://sh.rustup.rs .