add zigcc linker wrappers for cross-compiling musl bindeps

Artifact dependencies (fspy_test_bin) target linux-musl, which requires
a musl-capable linker. On non-Linux hosts, delegate to cargo-zigbuild's
zig cc via wrapper scripts in .cargo/.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: branchseer

.cargo/config.toml

@@ -3,3 +3,11 @@ rustflags = ["--cfg", "tokio_unstable"] # also update .github/workflows/ci.yml
 
 [unstable]
 bindeps = true
+
+# Linker wrappers for cross-compiling bindep targets (fspy_test_bin) via cargo-zigbuild.
+# On native Linux the system linker can handle musl targets; these are needed on non-Linux hosts.
+[target.x86_64-unknown-linux-musl]
+rustflags = ["-C", "linker=.cargo/zigcc-x86_64-unknown-linux-musl"]
+
+[target.aarch64-unknown-linux-musl]
+rustflags = ["-C", "linker=.cargo/zigcc-aarch64-unknown-linux-musl"]

.cargo/zigcc-aarch64-unknown-linux-musl

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec cargo-zigbuild zig cc -- -fno-sanitize=all -target aarch64-linux-musl "$@"

.cargo/zigcc-x86_64-unknown-linux-musl

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec cargo-zigbuild zig cc -- -fno-sanitize=all -target x86_64-linux-musl "$@"