game_activity/ffi: Drop cfg for inexistant target_arch = "armv7"

[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

android-activity/src/game_activity/ffi.rs

@@ -16,10 +16,7 @@ use jni_sys::*;
 use libc::{pthread_cond_t, pthread_mutex_t, pthread_t};
 use ndk_sys::{AAssetManager, AConfiguration, ALooper, ALooper_callbackFunc, ANativeWindow, ARect};
 
-#[cfg(all(
-    any(target_os = "android", feature = "test"),
-    any(target_arch = "arm", target_arch = "armv7")
-))]
+#[cfg(all(any(target_os = "android", feature = "test"), target_arch = "arm"))]
 include!("ffi_arm.rs");
 
 #[cfg(all(any(target_os = "android", feature = "test"), target_arch = "aarch64"))]