Add workaround for aarch64 Rust missing symbols

[ebeasant-arm]

When building for aarch64, cross or native,
linking with musl will fail due to missing symbols.

This change only affects Rust code targetting:
- aarch64-unknown-linux-musl

Workaround for:
rust-lang/compiler-builtins#201

Checklist

• Pull request affects core Oak functionality (e.g. runtime, SDK, ABI)
  • I have written tests that cover the code changes.
  • I have checked that these tests are run by
    Cloudbuild
  • I have updated documentation accordingly.
  • I have raised an issue to
    cover any TODOs and/or unfinished work.
• Pull request includes prototype/experimental work that is under
  construction.

[googlebot]

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[ebeasant-arm]

Waiting on CLA process to update, email address has been added 24/06/2020

[tiziano88]

Are you waiting for CLA update on Arm or Google side?

[tiziano88]

@googlebot ping

[ebeasant-arm]

I think its Google side - Guillaume tells me I've been added, and I'm in the Android Dev group too it seems.

[tiziano88]

What does https://cla.developers.google.com/clas show for you?

[ebeasant-arm]

What does https://cla.developers.google.com/clas show for you?

Takes me to the 'We don't have any individual Agreements for you on file", but this time it does give me the opportunity to press the 'employer' button. Will chase that rabbithole :-)

Edit: Doesn't seem to be the process I'm meant to follow - should already be on there. Guillaume did submit it with the email address capitalised ([email protected]), would that have caused issues?

[ebeasant-arm]

Sorted: CLA is done, shows up on the CLA system here (Covered by Corporate and also Android CLA) :- We did a remove and add of the email address to the relevant group.

[tiziano88]

@googlebot

[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[github-actions]

Reproducibility Index:

562715d812c1ed5397402d3f4b02b03addf416ccb4a8f071eac00a8015082b42  ./examples/target/wasm32-unknown-unknown/release/abitest_0_frontend.wasm
e89bb8621965e356156c939997a61fa1af30352159ae9e7a59f50a8eb101648d  ./examples/target/wasm32-unknown-unknown/release/abitest_1_backend.wasm
b256b1c1402a8f25381352047ee48cc9a07314d4227a64bd786369a17c61d1df  ./examples/target/wasm32-unknown-unknown/release/aggregator.wasm
44eff10ce70a232c84cc32c225e75eca695634abc9ecfbf543022aa0a5682cd7  ./examples/target/wasm32-unknown-unknown/release/chat.wasm
b28dc802af588ea6512974d2d9ec17557dd454f760b379ab80b11efbe444ecfd  ./examples/target/wasm32-unknown-unknown/release/hello_world.wasm
1123ddd109dd00155b0f59ccc2f3025974bacc82e15a4d1fe2a83ff6ceb2b3cd  ./examples/target/wasm32-unknown-unknown/release/machine_learning.wasm
66ae9e10c2d72cab7e629b2fea2ae98939649c391480ab255d589f5da8c7ae0f  ./examples/target/wasm32-unknown-unknown/release/private_set_intersection.wasm
0cd8cb0baae0c59852e775a697ca5408f975c1c1fdc53cc8f3a0e7d07e23f5af  ./examples/target/wasm32-unknown-unknown/release/running_average.wasm
15da62b4701e02ae731276dbe8bdfd29805871e7f863e8e15b1fe11983023159  ./examples/target/wasm32-unknown-unknown/release/translator.wasm
571d966c66ebf487d1f07ae0aba89fe22bcf8d09fcd861a490aec215c4b94aa9  ./examples/target/wasm32-unknown-unknown/release/trusted_information_retrieval.wasm
00bf32262f96d1da956c69eb9acfe116074dda5bcf22fd8eef3954b0a0d6ff0b  ./oak/server/target/x86_64-unknown-linux-musl/release/oak_loader

Reproducibility Index diff: