Take sys/vxworks/stack_overflow from sys/unix instead.

Author: m-ou-se

library/std/src/sys/unix/stack_overflow.rs

@@ -219,7 +219,7 @@ mod imp {
     target_os = "solaris",
     target_os = "illumos",
     all(target_os = "netbsd", not(target_vendor = "rumprun")),
-    target_os = "openbsd"
+    target_os = "openbsd",
 )))]
 mod imp {
     pub unsafe fn init() {}

library/std/src/sys/vxworks/mod.rs

@@ -28,6 +28,7 @@ pub mod process;
 pub mod rand;
 #[path = "../unix/rwlock.rs"]
 pub mod rwlock;
+#[path = "../unix/stack_overflow.rs"]
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;