makepkg: improve rust support
For Rust packages it is currently problematic to properly determine the build target, because Rust architecture and target triplets are different from CARCH
/CHOST
ones.
Addressed in FS#74399, a part of #3.
Details about Rust platform support: https://doc.rust-lang.org/rustc/platform-support.html
This MR introduces new RUSTARCH
and RUSTHOST
variables, so we can simply do cargo fetch --locked --target "$RUSTHOST"
inside PKGBUILD
s.
Edited by Hanabishi Recca