sys::sendfile enable it on solaris based systems (#2198)

* sys::sendfile enable it on solaris based systems

* changelog entry

Author: devnexen

changelog/2198.added.md

@@ -0,0 +1 @@
+Added `sys::sendfile` support for solaris/illumos.

src/sys/mod.rs

@@ -124,6 +124,8 @@ feature! {
     target_os = "freebsd",
     apple_targets,
     target_os = "linux",
+    target_os = "solaris",
+    target_os = "illumos",
 ))]
 feature! {
     #![feature = "zerocopy"]

src/sys/sendfile.rs

@@ -20,8 +20,9 @@ use crate::Result;
 ///
 /// `in_fd` must support `mmap`-like operations and therefore cannot be a socket.
 ///
-/// For more information, see [the sendfile(2) man page.](https://man7.org/linux/man-pages/man2/sendfile.2.html)
-#[cfg(any(target_os = "android", target_os = "linux"))]
+/// For more information, see [the sendfile(2) man page.](https://man7.org/linux/man-pages/man2/sendfile.2.html) for Linux,
+/// see [the sendfile(2) man page.](https://docs.oracle.com/cd/E88353_01/html/E37843/sendfile-3c.html) for Solaris.
+#[cfg(any(target_os = "android", target_os = "linux", target_os = "solaris", target_os = "illumos"))]
 pub fn sendfile<F1: AsFd, F2: AsFd>(
     out_fd: F1,
     in_fd: F2,