Unnecessary bindings for target_arch = "armv7"

[katyo]

As I know in rust target_arch = "arm" actually corresponding to armv7, so second bindings completely useless.
https://github.com/rust-windowing/android-ndk-rs/blob/a8ddfa4f7b510923cd69ded0f7e8492711b0af88/android-ndk-sys/src/lib.rs#L21-L28
Fix me if I'm wrong.

[dvc94ch]

maybe one is for thumb instructions and the other for the regular arm instructions, but not sure

[katyo]

Rust:

target	notes
arm-linux-androideabi	ARMv7 Android
armv7-linux-androideabi	ARMv7a Android
thumbv7neon-linux-androideabi	Thumb2-mode ARMv7a Android with NEON

https://forge.rust-lang.org/release/platform-support.html

Android NDK:

target	notes
armeabi-v7a	armeabi Thumb-2 VFPv3-D16

https://developer.android.com/ndk/guides/abis

I guess that generated bindings for all 32-bit ARMs will be the same.

[katyo]

target_arch =

"x86"
"x86_64"
"mips"
"powerpc"
"powerpc64"
"arm"
"aarch64"

https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch

[katyo]

I look at the compiler specs, the arch and data layout actually is same for all 32-bit ARMs:
arm, armv7, thumbv7neon.
To differentiate bindings by target kind we should check target_feature (ex. target_feature = "v7", target_feature = "thumb2", target_feature = "neon", and etc.)
But because generated bindings will be the same, so we actually don't need second section.

$ diff src/ffi_arm.rs src/ffi_armv7.rs