xrOS support

Swapped to visionOS target_os

(apply <rust-lang#3568> to `main`)
[resolve conflicts - Trevor]
(cherry picked from commit b5b0f69)

Author: agg23

Diff for: build.rs

@@ -21,7 +21,7 @@ const ALLOWED_CFGS: &'static [&'static str] = &[
 
 // Extra values to allow for check-cfg.
 const CHECK_CFG_EXTRA: &'static [(&'static str, &'static [&'static str])] = &[
-    ("target_os", &["switch", "aix", "ohos", "hurd"]),
+    ("target_os", &["switch", "aix", "ohos", "hurd", "visionos"]),
     ("target_env", &["illumos", "wasi", "aix", "ohos"]),
     (
         "target_arch",

Diff for: src/unix/bsd/apple/mod.rs

@@ -6427,7 +6427,7 @@ cfg_if! {
     }
 }
 cfg_if! {
-    if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos"))] {
+    if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "visionos"))] {
         extern "C" {
             pub fn memmem(
                 haystack: *const ::c_void,

Diff for: src/unix/bsd/mod.rs

@@ -39,6 +39,7 @@ s! {
                       target_os = "ios",
                       target_os = "tvos",
                       target_os = "watchos",
+                      target_os = "visionos",
                       target_os = "netbsd",
                       target_os = "openbsd")))]
         pub pw_fields: ::c_int,
@@ -921,10 +922,8 @@ cfg_if! {
             pub fn syscall(num: ::c_int, ...) -> ::c_int;
         }
     }
-}
 
-cfg_if! {
-    if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))] {
+    if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos", target_os = "visionos"))] {
         mod apple;
         pub use self::apple::*;
     } else if #[cfg(any(target_os = "openbsd", target_os = "netbsd"))] {

Diff for: src/unix/mod.rs

@@ -381,6 +381,7 @@ cfg_if! {
                         target_os = "ios",
                         target_os = "tvos",
                         target_os = "watchos",
+                        target_os = "visionos",
                         target_os = "android",
                         target_os = "openbsd",
                         target_os = "nto",
@@ -1043,7 +1044,8 @@ extern "C" {
             target_os = "macos",
             target_os = "ios",
             target_os = "tvos",
-            target_os = "watchos"
+            target_os = "watchos",
+            target_os = "visionos"
         ),
         link_name = "realpath$DARWIN_EXTSN"
     )]
@@ -1218,7 +1220,8 @@ extern "C" {
             target_os = "macos",
             target_os = "ios",
             target_os = "tvos",
-            target_os = "watchos"
+            target_os = "watchos",
+            target_os = "visionos"
         ),
         link_name = "res_9_init"
     )]
@@ -1581,6 +1584,7 @@ cfg_if! {
                         target_os = "ios",
                         target_os = "tvos",
                         target_os = "watchos",
+                        target_os = "visionos",
                         target_os = "freebsd",
                         target_os = "dragonfly",
                         target_os = "openbsd",