Unify cygwin & horizon random impl

Author: Berrysoft

library/std/src/random.rs

@@ -37,7 +37,7 @@ use crate::sys::random as sys;
 /// Solaris                | [`arc4random_buf`](https://docs.oracle.com/cd/E88353_01/html/E37843/arc4random-3c.html)
 /// Vita                   | `arc4random_buf`
 /// Hermit                 | `read_entropy`
-/// Horizon                | `getrandom` shim
+/// Horizon, Cygwin        | `getrandom`
 /// AIX, Hurd, L4Re, QNX   | `/dev/urandom`
 /// Redox                  | `/scheme/rand`
 /// RTEMS                  | [`arc4random_buf`](https://docs.rtems.org/branches/master/bsp-howto/getentropy.html)

library/std/src/sys/random/cygwin.rs

@@ -6,9 +6,6 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "windows")] {
         mod windows;
         pub use windows::fill_bytes;
-    } else if #[cfg(target_os = "cygwin")] {
-        mod cygwin;
-        pub use cygwin::fill_bytes;
     } else if #[cfg(target_vendor = "apple")] {
         mod apple;
         pub use apple::fill_bytes;
@@ -38,10 +35,10 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "hermit")] {
         mod hermit;
         pub use hermit::fill_bytes;
-    } else if #[cfg(target_os = "horizon")] {
-        // FIXME: add arc4random_buf to shim-3ds
-        mod horizon;
-        pub use horizon::fill_bytes;
+    } else if #[cfg(any(target_os = "horizon", target_os = "cygwin"))] {
+        // FIXME(horizon): add arc4random_buf to shim-3ds
+        mod getrandom;
+        pub use getrandom::fill_bytes;
     } else if #[cfg(any(
         target_os = "aix",
         target_os = "hurd",