don't allocate serial_ops

don't allocate serial_ops

Now that struct serial_ops is const everywhere, we can easily turn the
instances into globals.  This patch implements this idea.

On the one hand I think this is nicer since it makes a bit more data
readonly and slightly reduces allocations.  On the other hand it
reduces readability somewhat.

If the readability is a concern to anyone I was thinking I could write
a macro that conditionally uses GCC's designated initializer
extension.

Tested by rebuilding on x86-64 Fedora 18, both natively and using the
mingw cross tools.

2013-12-19  Tom Tromey  <tromey@redhat.com>

	* ser-unix.c (hardwire_ops): New global.
	(_initialize_ser_hardwire): Use it.
	* ser-tcp.c (tcp_ops): New global.
	(_initialize_ser_tcp): Use it.
	* ser-pipe.c (pipe_ops): New global.
	(_initialize_ser_pipe): Use it.
	* ser-mingw.c (hardwire_ops, tty_ops, pipe_ops, tcp_ops): New
	globals.
	(_initialize_ser_windows): Use them.