OpenBSD: add ppoll

(backport <#4957>)
(cherry picked from commit 9c7cb28)

Author: kotauskas

libc-test/semver/openbsd.txt

@@ -1253,6 +1253,7 @@ posix_spawnattr_setschedpolicy
 posix_spawnattr_setsigdefault
 posix_spawnattr_setsigmask
 posix_spawnp
+ppoll
 preadv
 pseudo_AF_HDRCMPLT
 pseudo_AF_PFLOW

src/unix/bsd/netbsdlike/mod.rs

@@ -734,6 +734,12 @@ extern "C" {
         param: *mut sched_param,
     ) -> c_int;
     pub fn pipe2(fds: *mut c_int, flags: c_int) -> c_int;
+    pub fn ppoll(
+        fds: *mut crate::pollfd,
+        nfds: crate::nfds_t,
+        ts: *const crate::timespec,
+        sigmask: *const crate::sigset_t,
+    ) -> c_int;
 
     pub fn getgrouplist(
         name: *const c_char,

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -2195,12 +2195,6 @@ extern "C" {
         ts: *const crate::timespec,
         sigmask: *const crate::sigset_t,
     ) -> c_int;
-    pub fn ppoll(
-        fds: *mut crate::pollfd,
-        nfds: crate::nfds_t,
-        ts: *const crate::timespec,
-        sigmask: *const crate::sigset_t,
-    ) -> c_int;
     pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
 
     pub fn reboot(mode: c_int, bootstr: *mut c_char) -> c_int;