Fix fp ABI for C guest

[ludfjig]

Update guest C api to use cargo hyperlight build which will use the right target. This fixes the previous ABI mismatch where clang used fp registers to pass floats, but rust didn't.

Note: To compile simpleguest/main.c, we're still using clang's x86_64-unknown-linux-none target

Closes #179

** For the curious, a small repro can be found here https://github.com/ludfjig/float-abi-test

[Copilot]

Pull request overview

This PR fixes the float ABI mismatch in the C guest path by switching the guest C API build to use cargo hyperlight build (which selects the correct target/ABI), and re-enables the previously ignored float roundtrip test with comparisons that tolerate FlatBuffers’ -0.0 behavior.

Changes:

• Build hyperlight_guest_capi via cargo hyperlight build and update artifact paths to x86_64-hyperlight-none.
• Re-enable float_roundtrip and adjust float comparisons to handle -0.0 and NaN.
• Update a test guest lockfile dependency (quote 1.0.43 → 1.0.44).

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/tests/rust_guests/witguest/Cargo.lock	Bumps quote dependency version/checksum in the witguest lockfile.
src/hyperlight_host/tests/sandbox_host_tests.rs	Un-ignores float_roundtrip and adjusts float equality checks for -0.0/NaN.
src/hyperlight_guest_capi/.cargo/config.toml	Removes hardcoded target/profile panic settings so builds are driven by cargo-hyperlight.
c.just	Switches C API build to cargo hyperlight build and updates link search path to the new target dir.
Justfile	Updates packaged static lib paths to target/x86_64-hyperlight-none/....

[jsturtevant]

This fixes the previous ABI mismatch where clang used fp registers to pass floats, but rust didn't.

Great find! I've was wondering why this was still failing. Specifically this means that it was using C was using xxm registers and rust was using soft-float because it was built in no std? With Cargo hyperlight the rust code will use the xxm registers which aligns with the c code.

[dblnz]

LGTM! Good catch!