Auto merge of #2247 - sunfishcode:sunfishcode/pollrdhup, r=Amanieu

Define `POLLRDHUP` for Linux.

`POLLRDHUP` is a Linux-specific extension introduced in Linux 2.6.17.

It's documented in the [Linux `poll` man page].

[Linux `poll` man page]: https://man7.org/linux/man-pages/man2/poll.2.html

Author: bors

src/unix/linux_like/linux/mod.rs

@@ -3036,6 +3036,11 @@ pub const SOL_CAN_BASE: ::c_int = 100;
 pub const CAN_INV_FILTER: canid_t = 0x20000000;
 pub const CAN_RAW_FILTER_MAX: ::c_int = 512;
 
+#[cfg(not(any(target_arch = "sparc", target_arch = "sparc64")))]
+pub const POLLRDHUP: ::c_int = 0x2000;
+#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
+pub const POLLRDHUP: ::c_int = 0x800;
+
 f! {
     pub fn NLA_ALIGN(len: ::c_int) -> ::c_int {
         return ((len) + NLA_ALIGNTO - 1) & !(NLA_ALIGNTO - 1)