fix tcgetsid return type

[Christopher Faylor]

On Mon, Feb 27, 2012 at 04:25:36PM -0700, Eric Blake wrote:
>Detected by gnulib's unit tests.  POSIX requires tcgetsid to return
>pid_t, not int.
>
>2012-02-27  Eric Blake  <eblake@redhat.com>
>
>	* include/sys/termios.h (tcgetsid): Fix return type.
>	* termios.cc (tcgetsid): Likewise.
>	* fhandler_termios.cc (fhandler_termios::tcgetsid): Likewise.
>	* fhandler.h (fhandler_base): Likewise.
>	* fhandler.cc (fhandler_base::tcgetsid): Likewise.

Looks good.  Please check in.

cgf