Fix cfg target checks for TcpKeepalive

This brings the checks on the setters of TcpKeepalive
in line with the actual support in sys::set_tcp_keepalive().

(cherry picked from commit 14e99cf)

Author: MortronMeymo

src/lib.rs

@@ -374,9 +374,11 @@ impl TcpKeepalive {
     #[cfg(all(
         feature = "all",
         any(
+            target_os = "android",
             target_os = "dragonfly",
             target_os = "freebsd",
             target_os = "fuchsia",
+            target_os = "illumos",
             target_os = "linux",
             target_os = "netbsd",
             target_vendor = "apple",
@@ -388,8 +390,11 @@ impl TcpKeepalive {
         doc(cfg(all(
             feature = "all",
             any(
+                target_os = "android",
+                target_os = "dragonfly",
                 target_os = "freebsd",
                 target_os = "fuchsia",
+                target_os = "illumos",
                 target_os = "linux",
                 target_os = "netbsd",
                 target_vendor = "apple",
@@ -412,9 +417,11 @@ impl TcpKeepalive {
         feature = "all",
         any(
             doc,
+            target_os = "android",
             target_os = "dragonfly",
             target_os = "freebsd",
             target_os = "fuchsia",
+            target_os = "illumos",
             target_os = "linux",
             target_os = "netbsd",
             target_vendor = "apple",
@@ -425,8 +432,11 @@ impl TcpKeepalive {
         doc(cfg(all(
             feature = "all",
             any(
+                target_os = "android",
+                target_os = "dragonfly",
                 target_os = "freebsd",
                 target_os = "fuchsia",
+                target_os = "illumos",
                 target_os = "linux",
                 target_os = "netbsd",
                 target_vendor = "apple",