Auto merge of #63744 - Centril:rollup-g4l3ra9, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #63216 (avoid unnecessary reservations in std::io::Take::read_to_end)
 - #63265 (Implement `nth_back` for ChunksExactMut)
 - #63691 (Fix bug in iter::Chain::size_hint)
 - #63722 (Don't use stage naming in RUSTFLAGS environment variables)
 - #63723 (Consolidate sigemptyset workarounds)
 - #63736 (Restore the rustc_plugin crate in the sysroot)
 - #63743 (Allow git to merge `Cargo.lock`)

Failed merges:

r? @ghost

1 files changed, 24 insertions, 30 deletions

diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index 6bb20bbe087..21fca23a8fe 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -20,6 +20,30 @@ cfg_if::cfg_if! {
     }
 }
 
+// Android with api less than 21 define sig* functions inline, so it is not
+// available for dynamic link. Implementing sigemptyset and sigaddset allow us
+// to support older Android version (independent of libc version).
+// The following implementations are based on https://git.io/vSkNf
+cfg_if::cfg_if! {
+    if #[cfg(target_os = "android")] {
+        pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
+            set.write_bytes(0u8, 1);
+            return 0;
+        }
+        #[allow(dead_code)]
+        pub unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
+            use crate::{slice, mem};
+
+            let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<libc::sigset_t>());
+            let bit = (signum - 1) as usize;
+            raw[bit / 8] |= 1 << (bit % 8);
+            return 0;
+        }
+    } else {
+        pub use libc::{sigemptyset, sigaddset};
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Command
 ////////////////////////////////////////////////////////////////////////////////
@@ -429,36 +453,6 @@ mod tests {
         }
     }
 
-    // Android with api less than 21 define sig* functions inline, so it is not
-    // available for dynamic link. Implementing sigemptyset and sigaddset allow us
-    // to support older Android version (independent of libc version).
-    // The following implementations are based on https://git.io/vSkNf
-
-    #[cfg(not(target_os = "android"))]
-    extern {
-        #[cfg_attr(target_os = "netbsd", link_name = "__sigemptyset14")]
-        fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int;
-
-        #[cfg_attr(target_os = "netbsd", link_name = "__sigaddset14")]
-        fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int;
-    }
-
-    #[cfg(target_os = "android")]
-    unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
-        set.write_bytes(0u8, 1);
-        return 0;
-    }
-
-    #[cfg(target_os = "android")]
-    unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
-        use crate::slice;
-
-        let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<libc::sigset_t>());
-        let bit = (signum - 1) as usize;
-        raw[bit / 8] |= 1 << (bit % 8);
-        return 0;
-    }
-
     // See #14232 for more information, but it appears that signal delivery to a
     // newly spawned process may just be raced in the macOS, so to prevent this
     // test from being flaky we ignore it on macOS.