Throughout, remove extra space after function name from debugging output.

Throughout, change syscalls to report on return values using new %R format
option.
* smallprint.cc (__small_vsprintf): Add parsing for %R to report on return
values and possible errno from syscalls.
* errno.cc (errmap): Add PRIVILEGE_NOT_HELD.
* fhandler_tty.cc (fhandler_pty_master::setup): When creating a thread use
shorter name to reduce debuggging output.
* select.cc (start_thread_pipe): Ditto.
(start_thread_serial): Ditto.
(start_thread_socket): Ditto.
(start_thread_mailslot): Ditto.
* sigproc.cc (talktome): Ditto.

winsup/cygwin/fork.cc

@@ -685,7 +685,7 @@ fork ()
 
       set_errno (grouped.this_errno);
     }
-  syscall_printf ("%d = fork()", res);
+  syscall_printf ("%R = fork()", res);
   return res;
 }
 #ifdef DEBUGGING