[XrdCl] Add missing header
[XrdSys] Fix a race in the LinuxSemaphore
Fix problem with creation of the forwarded ticket

Following commit f44d455d78109794a46714764cd57e79bc105969 the daemon is no longer
able to set {uid,gid} on the created file with the forwarded ticket. This patch
completes the previous one by removing the attempt to change {uid,gid}. The file
will be pwn by the daemon owner with permissions 0600.