Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

vendor/rustix/src/backend/libc/process/wait.rs

@@ -0,0 +1,9 @@
+use crate::backend::c;
+
+pub(crate) use c::{
+    WCONTINUED, WEXITSTATUS, WIFCONTINUED, WIFEXITED, WIFSIGNALED, WIFSTOPPED, WNOHANG, WSTOPSIG,
+    WTERMSIG, WUNTRACED,
+};
+
+#[cfg(not(any(target_os = "openbsd", target_os = "redox", target_os = "wasi")))]
+pub(crate) use c::{WEXITED, WNOWAIT, WSTOPPED};