redox: define SCM_RIGHTS

Author: jackpot51

libc-test/semver/redox.txt

@@ -135,6 +135,7 @@ O_SHLOCK
 O_SYMLINK
 PTHREAD_STACK_MIN
 SA_RESTORER
+SCM_RIGHTS
 SIGIO
 SIGPWR
 SIGSTKFLT

src/unix/redox/mod.rs

@@ -782,6 +782,7 @@ pub const MSG_PEEK: c_int = 2;
 pub const MSG_TRUNC: c_int = 32;
 pub const MSG_DONTWAIT: c_int = 64;
 pub const MSG_WAITALL: c_int = 256;
+pub const SCM_RIGHTS: c_int = 1;
 pub const SHUT_RD: c_int = 0;
 pub const SHUT_WR: c_int = 1;
 pub const SHUT_RDWR: c_int = 2;