Build on Android

[thedataking]

Required to quantify performance impact on phones. Scoped to aarch64 for now.

• provision and build in CI
• provision emulator and test the binaries we produce

[thedataking]

Prerequisites:

• Fixes on perl/build-on-android branch.
• Rust build needs NDK 25 or later (I tested with 26.3.11579264 downloaded from this page).

Building dav1d (adjust paths as necessary):

PATH=$HOME/android_sdk/ndk/26.3.11579264/toolchains/llvm/prebuilt/linux-x86_64/bin/:$PATH \
meson build --buildtype release \
            --werror \
            --libdir lib \
            --prefix "$(pwd)/build/dav1d_install" \
            --cross-file package/crossfiles/aarch64-android.meson \
            -Ddefault_library=both \
            -Dtrim_dsp=false \
            -Dtest_rust=false

NOTE: only pass -Dtest_rust=false if building the C version from the rav1d repo. See #825 for details.

Building rav1d:

PATH="$HOME/android_sdk/ndk/26.3.11579264/toolchains/llvm/prebuilt/linux-x86_64/bin:$PATH" \
    RUSTFLAGS="-C linker=aarch64-linux-android26-clang -L $HOME/android_sdk/ndk/26.3.11579264/toolchains/llvm/prebuilt/linux-x86_64/lib/clang/17/lib/linux/aarch64 -L $HOME/android_sdk/ndk/26.3.11579264/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/26" \
    AR=llvm-ar \
    CC=aarch64-linux-android26-clang \
    cargo build --target aarch64-linux-android --release

[thedataking]

Commands to build with NDK 2.7 RC:

PATH=$HOME/android_sdk/ndk/27.0.11902837/toolchains/llvm/prebuilt/linux-x86_64/bin:$PATH \
meson build --buildtype release \
            --werror \
            --libdir lib \
            --prefix "$(pwd)/build/dav1d_install" \
            --cross-file package/crossfiles/aarch64-android.meson \
            -Ddefault_library=both \
            -Dtrim_dsp=false \
            -Dtest_rust=false

PATH=$HOME/android_sdk/ndk/27.0.11902837/toolchains/llvm/prebuilt/linux-x86_64/bin:$PATH \
RUSTFLAGS="-C linker=aarch64-linux-android27-clang -L $HOME/android_sdk/ndk/27.0.11902837/toolchains/llvm/prebuilt/linux-x86_64/lib/clang/17/lib/linux/aarch64 -L $HOME/android_sdk/ndk/27.0.11902837/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/27" \
    AR=llvm-ar \
    CC=aarch64-linux-android27-clang \
    cargo build --target aarch64-linux-android --release