epoll: add busy polling parameters

In Linux 6.9 a new ioctl for epoll was added:
https://man.archlinux.org/man/ioctl_eventpoll.2.en

Add support for it. The ioctls constants are padded to
64 bits alignment even on 32 bits machines.

Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>

(backport <rust-lang#3922>)
(cherry picked from commit fb58c01)

Signed-off-by: Trevor Gross <tmgross@umich.edu>

Author: tammela

libc-test/build.rs

@@ -4260,6 +4260,10 @@ fn test_linux(target: &str) {
             // FIXME: Requires >= 6.11 kernel headers.
             "MAP_DROPPABLE" => true,
 
+            // FIXME: Requires >= 6.9 kernel headers.
+            "EPIOCSPARAMS"
+            | "EPIOCGPARAMS" => true,
+
             _ => false,
         }
     });

src/unix/linux_like/linux/mod.rs

@@ -1486,6 +1486,15 @@ cfg_if! {
             }
         }
     }
+
+    // #include <linux/eventpoll.h>
+
+    pub struct epoll_params {
+        pub busy_poll_usecs: u32,
+        pub busy_poll_budget: u16,
+        pub prefer_busy_poll: u8,
+        pub __pad: u8, // Must be zero
+    }
 }
 
 s_no_extra_traits! {