define IPV6_HOPLIMIT for freebsd, linux, and macos

Author: wg

src/unix/bsd/apple/mod.rs

@@ -2253,6 +2253,7 @@ pub const IPV6_CHECKSUM: ::c_int = 26;
 pub const IPV6_RECVTCLASS: ::c_int = 35;
 pub const IPV6_TCLASS: ::c_int = 36;
 pub const IPV6_PKTINFO: ::c_int = 46;
+pub const IPV6_HOPLIMIT: ::c_int = 47;
 pub const IPV6_RECVPKTINFO: ::c_int = 61;
 
 pub const TCP_NOPUSH: ::c_int = 4;

src/unix/bsd/freebsdlike/mod.rs

@@ -760,6 +760,7 @@ pub const IPV6_LEAVE_GROUP: ::c_int = 13;
 pub const IPV6_CHECKSUM: ::c_int = 26;
 pub const IPV6_RECVPKTINFO: ::c_int = 36;
 pub const IPV6_PKTINFO: ::c_int = 46;
+pub const IPV6_HOPLIMIT: ::c_int = 47;
 pub const IPV6_RECVTCLASS: ::c_int = 57;
 pub const IPV6_TCLASS: ::c_int = 61;
 

src/unix/linux_like/mod.rs

@@ -805,6 +805,7 @@ pub const IPV6_JOIN_ANYCAST: ::c_int = 27;
 pub const IPV6_LEAVE_ANYCAST: ::c_int = 28;
 pub const IPV6_RECVPKTINFO: ::c_int = 49;
 pub const IPV6_PKTINFO: ::c_int = 50;
+pub const IPV6_HOPLIMIT: ::c_int = 52;
 pub const IPV6_RECVTCLASS: ::c_int = 66;
 pub const IPV6_TCLASS: ::c_int = 67;