`enable-patchelf` build-attribute uses `ld` for the build-on host, not the build-for host

[lengau]

Bug Description

When cross-compiling uv on arm64 for armhf and enabling patchelf, I end up with a 32-bin ARM executable that's interpreted with /snap/core24/current/lib/ld-linux-aarch64.so.1 rather than /snap/core24/current/lib/ld-linux-armhf.so.3.

To Reproduce

Try building uv-snap from the candidate-armhf branch.

Environment

n/a

snapcraft.yaml

https://github.com/lengau/uv-snap/tree/candidate-armhf

Relevant log output

n/a

Additional context

No response