Cygwin: pty: Fix handle leak in master process.

If non-cygwin process is started in pty, closing from_master_nat
pipe handle was missing in fhandler_pty_slave::input_transfer().
This occured because the handle was duplicated but not closed.

https://github.com/msys2/msys2-runtime/issues/198

Fixes: 29431fcb5b ("Cygwin: pty: Inherit typeahead data between two input pipes.")
Reported-by: Hakkin Lain
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

winsup/cygwin/fhandler/pty.cc

@@ -3995,6 +3995,7 @@ fhandler_pty_slave::transfer_input (tty::xfer_dir dir, HANDLE from, tty *ttyp,
 	    transfered = true;;
 	}
     }
+  CloseHandle (to);
 
   /* Fix input_available_event which indicates availability in cyg pipe. */
   if (dir == tty::to_nat) /* all data is transfered to nat pipe,

winsup/cygwin/release/3.5.1

@@ -12,3 +12,7 @@ Fixes:
   error mode is now possible by using the new CYGWIN environment variable
   option "winjitdebug".
   Addresses: https://cygwin.com/pipermail/cygwin/2024-February/255305.html
+
+- Fix handle leak in pty master which occurs when non-cygwin process
+  is started in pty.
+  Addresses: https://github.com/msys2/msys2-runtime/issues/198