Let mimalloc_rust link libatomic

mimalloc_rust now links libatomic itself on targets without 64-bit
atomics, so cli/build.rs, which did that for 32-bit PowerPC hosts, is
no longer needed.

Cargo.lock

@@ -189,7 +189,7 @@ checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 [[package]]
 name = "libmimalloc-sys"
 version = "0.1.49"
-source = "git+https://github.com/rui314/mimalloc_rust?rev=3979460494f1cd1e7f936cb8e10f41e927c9f698#3979460494f1cd1e7f936cb8e10f41e927c9f698"
+source = "git+https://github.com/rui314/mimalloc_rust?rev=d4636c9f420065b29306de9deb128b7fa162892c#d4636c9f420065b29306de9deb128b7fa162892c"
 dependencies = [
  "cc",
 ]
@@ -224,7 +224,7 @@ dependencies = [
 [[package]]
 name = "mimalloc"
 version = "0.1.52"
-source = "git+https://github.com/rui314/mimalloc_rust?rev=3979460494f1cd1e7f936cb8e10f41e927c9f698#3979460494f1cd1e7f936cb8e10f41e927c9f698"
+source = "git+https://github.com/rui314/mimalloc_rust?rev=d4636c9f420065b29306de9deb128b7fa162892c#d4636c9f420065b29306de9deb128b7fa162892c"
 dependencies = [
  "libmimalloc-sys",
 ]

cli/Cargo.toml

@@ -39,7 +39,7 @@ mold-target-loongarch32 = { path = "../arch/loongarch32", optional = true }
 
 # sparc64 uses the system allocator. See main.rs.
 [target.'cfg(not(target_arch = "sparc64"))'.dependencies]
-mimalloc = { git = "https://github.com/rui314/mimalloc_rust", rev = "3979460494f1cd1e7f936cb8e10f41e927c9f698" }
+mimalloc = { git = "https://github.com/rui314/mimalloc_rust", rev = "d4636c9f420065b29306de9deb128b7fa162892c" }
 
 [dev-dependencies]
 mold-tests = { path = "../tests" }

cli/build.rs

@@ -1,15 +0,0 @@
-//! Links libatomic into mold on hosts without 64-bit atomics, such as
-//! 32-bit PowerPC. mimalloc uses 64-bit atomics, which C compilers
-//! implement as calls into libatomic on those hosts.
-
-fn main() {
-    println!("cargo:rerun-if-changed=build.rs");
-
-    let widths = std::env::var("CARGO_CFG_TARGET_HAS_ATOMIC").unwrap_or_default();
-    if !widths.split(',').any(|w| w == "64") {
-        // rustc places libraries named by this crate before its dependencies
-        // on the linker command line, where --as-needed would drop libatomic.
-        // Link arguments come after all libraries.
-        println!("cargo:rustc-link-arg-bins=-latomic");
-    }
-}