[WIP] Run cross build for rmm targeting aarch64

[Copilot]

Fix PyO3 cross-compilation issue for aarch64 binary builds

Problem:
The cross-compilation build for aarch64-unknown-linux-gnu target fails with "no Python 3.x interpreter found" error, even though PYO3_NO_PYTHON=1 is set. This happens because the project has both a Python extension module (cdylib) and a standalone binary, but PyO3 dependencies are always included even when building only the binary.

Solution Plan:

• Analyze the issue and identify root cause
• Make PyO3 dependencies optional using Cargo features
• Create a python-extension feature flag
• Configure lib.rs to require the feature
• Update workflow to build binary without PyO3 feature
• Test the build locally
• Verify complete build process

Original prompt

一而再再而三的犯相同错误，请你Run cross build --bin rmm --release --target aarch64-unknown-linux-gnu
cross build --bin rmm --release --target aarch64-unknown-linux-gnu
shell: /usr/bin/bash -e {0}
env:
CARGO_HOME: /home/runner/.cargo
CARGO_INCREMENTAL: 0
CARGO_TERM_COLOR: always
PYO3_NO_PYTHON: 1
info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'

stable-x86_64-unknown-linux-gnu unchanged - rustc 1.91.0 (f8297e351 2025-10-28)

info: downloading component 'rust-src'
info: installing component 'rust-src'
Unable to find image 'ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main' locally
main: Pulling from cross-rs/aarch64-unknown-linux-gnu
13b7e930469f: Already exists
95c03b590ba5: Pulling fs layer
4032e298dfa7: Pulling fs layer
f95be9d81026: Pulling fs layer
5388263d2757: Pulling fs layer
5c55577d583a: Pulling fs layer
1df210121449: Pulling fs layer
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9062befda244: Pulling fs layer
34c6b57bdcfe: Pulling fs layer
ba76f0fd8172: Pulling fs layer
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61680dc25951: Pulling fs layer
087cfbda1bf9: Pulling fs layer
d55d9ada39b4: Pulling fs layer
4ac9fb53dff2: Pulling fs layer
11737bb648a7: Pulling fs layer
5c55577d583a: Waiting
1df210121449: Waiting
65153096ae1e: Waiting
b1cdb46abc7b: Waiting
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9062befda244: Waiting
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ba76f0fd8172: Waiting
4ac9fb53dff2: Waiting
e4fb9dc53e71: Waiting
11737bb648a7: Waiting
f95be9d81026: Verifying Checksum
f95be9d81026: Download complete
95c03b590ba5: Verifying Checksum
95c03b590ba5: Download complete
95c03b590ba5: Pull complete
5c55577d583a: Verifying Checksum
5c55577d583a: Download complete
5388263d2757: Verifying Checksum
5388263d2757: Download complete
1df210121449: Verifying Checksum
1df210121449: Download complete
b1cdb46abc7b: Verifying Checksum
b1cdb46abc7b: Download complete
e7710502a16d: Verifying Checksum
e7710502a16d: Download complete
9062befda244: Verifying Checksum
9062befda244: Download complete
65153096ae1e: Verifying Checksum
65153096ae1e: Download complete
ba76f0fd8172: Verifying Checksum
ba76f0fd8172: Download complete
e4fb9dc53e71: Verifying Checksum
e4fb9dc53e71: Download complete
61680dc25951: Download complete
087cfbda1bf9: Verifying Checksum
087cfbda1bf9: Download complete
d55d9ada39b4: Verifying Checksum
d55d9ada39b4: Download complete
4ac9fb53dff2: Verifying Checksum
4ac9fb53dff2: Download complete
11737bb648a7: Download complete
4032e298dfa7: Verifying Checksum
4032e298dfa7: Download complete
34c6b57bdcfe: Verifying Checksum
34c6b57bdcfe: Download complete
4032e298dfa7: Pull complete
f95be9d81026: Pull complete
5388263d2757: Pull complete
5c55577d583a: Pull complete
1df210121449: Pull complete
65153096ae1e: Pull complete
b1cdb46abc7b: Pull complete
e7710502a16d: Pull complete
9062befda244: Pull complete
34c6b57bdcfe: Pull complete
ba76f0fd8172: Pull complete
e4fb9dc53e71: Pull complete
61680dc25951: Pull complete
087cfbda1bf9: Pull complete
d55d9ada39b4: Pull complete
4ac9fb53dff2: Pull complete
11737bb648a7: Pull complete
Digest: sha256:a97f6370889c59f9b3d2ef8be5eeadfede8e4b0b31da53bc421f235244d09038
Status: Downloaded newer image for ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main
Compiling libc v0.2.172
Compiling proc-macro2 v1.0.95
Compiling unicode-ident v1.0.18
Compiling shlex v1.3.0
Compiling pkg-config v0.3.32
Compiling cfg-if v1.0.1
Compiling stable_deref_trait v1.2.0
Compiling target-lexicon v0.13.2
Compiling quote v1.0.40
Compiling version_check v0.9.5
Compiling syn v2.0.102
Compiling jobserver v0.1.33
Compiling typenum v1.18.0
Compiling cc v1.2.26
Compiling generic-array v0.14.7
Compiling pyo3-build-config v0.26.0
error: failed to run custom build command for pyo3-build-config v0.26.0

Caused by:
process didn't exit successfully: /target/release/build/pyo3-build-config-64875cbe5ab60d38/build-script-build (exit status: 1)
--- stdout
cargo:rerun-if-env-changed=PYO3_CONFIG_FILE
cargo:rerun-if-env-changed=PYO3_NO_PYTHON
cargo:rerun-if-env-changed=PYO3_ENVIRONMENT_SIGNATURE
cargo:rerun-if-env-changed=PYO3_PYTHON
cargo:rerun-if-env-changed=VIRTUAL_ENV
cargo:rerun-if-env-changed=CONDA_PREFIX
cargo:rerun-if-env-changed=PATH

--- stderr
error: no Python 3.x interpreter found
warning: build failed, waiting for other jobs to finish...
Error: Process completed with exit code 101.}

修正后，进行完备的验证！

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