[Rust 1.80 from July 25th 2024] points out that `armv7` is not a known,
valid value for the `target_arch` cfg variable.  This is confirmed by
the docs not listing it either:
https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch

Hence drop this entirely, and rely purely on `target_arch = "arm"`.

[Rust 1.80 from July 25th 2024]: https://blog.rust-lang.org/2024/07/25/Rust-1.80.0.html

…test`

Some code copied from the NDK carried over the respective `feature`
`cfg` guards, without ever adding the feature to the `[features]` list
in `Cargo.toml`.  Now that Rust detects these mishaps, we can fix it
by removing `test` (bindings don't seem to be run-tested) and reexpose
`ConfigurationRef::screen_round()` which was behind a previously
unsettable `feature = "api-level-30"`.

Also remove `unsafe impl Send/Sync for ConfigurationRef` since the
upstream `ndk` already declares `Configuration` to be `Send` and `Sync`,
and `RwLock` and `Arc` carry that through.

…ndSync` and unwritten `redraw_needed` field