Do an explicit cast that doesn't make sense

I don't know why this is what the compiler wants,
given that the docs say it shouldn't need a cast,
but this is for some reason what the compiler wants.

crates/cli_testing_examples/platform-switching/rust-platform/src/lib.rs

@@ -80,7 +80,7 @@ pub unsafe extern "C" fn roc_shm_open(
     oflag: libc::c_int,
     mode: libc::mode_t,
 ) -> libc::c_int {
-    libc::shm_open(name, oflag, mode as _)
+    libc::shm_open(name, oflag, mode as libc::c_uint)
 }
 
 #[cfg(unix)]