Make task_info as macos specific (#32693)

rust-analyzer breaks on Linux (when invoked without mach), because it
tries to compile the c files, and doesn't find `mach_init.h`
Since we don't need task_info on non-mac platforms, just make the
crate empty on other platforms.

Signed-off-by: Jonathan Schwender <jonathan.schwender@huawei.com>

support/rust-task_info/build.rs

@@ -3,7 +3,11 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 fn main() {
-    cc::Build::new()
-        .file("src/task_info.c")
-        .compile("libtask_info.a");
+    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
+
+    if target_os == "macos" {
+        cc::Build::new()
+            .file("src/task_info.c")
+            .compile("libtask_info.a");
+    }
 }

support/rust-task_info/src/lib.rs

@@ -6,8 +6,7 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
+//! A helper crate to get task information on macos.
 
-#![crate_name = "task_info"]
-#![crate_type = "rlib"]
-
+#[cfg(target_os = "macos")]
 pub mod task_basic_info;