remove struct fields because build failure

Author: Andrew Salmon

src/unix/notbsd/linux/mod.rs

@@ -232,11 +232,12 @@ s! {
         pub sem_flg: ::c_short,
     }
 
+    // FIXME
     pub struct semid_ds {
-        pub sem_perm: ::ipc_perm,
-        pub sem_otime: ::time_t,
-        pub sem_ctime: ::time_t,
-        pub sem_nsems: ::c_ulong,
+        // pub sem_perm: ::ipc_perm,
+        // pub sem_otime: ::time_t,
+        // pub sem_ctime: ::time_t,
+        // pub sem_nsems: ::c_ulong,
     }
 }