target/sh4: Deprecate the shix machine

The shix machine has been designed and used at Télécom Paris from 2003
to 2010. It had been added to QEMU in 2005 and has not been maintained
since. Since nobody is using the physical board anymore nor interested
in maintaining the QEMU port, it is time to deprecate it.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240109083053.2581588-2-sam@rfc1149.net>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

docs/about/deprecated.rst

@@ -269,6 +269,11 @@ Nios II ``10m50-ghrd`` and ``nios2-generic-nommu`` machines (since 8.2)
 
 The Nios II architecture is orphan.
 
+``shix`` (since 9.0)
+''''''''''''''''''''
+
+The machine is no longer in existence and has been long unmaintained
+in QEMU.
 
 Backend options
 ---------------

hw/sh4/shix.c

@@ -80,6 +80,7 @@ static void shix_machine_init(MachineClass *mc)
     mc->init = shix_init;
     mc->is_default = true;
     mc->default_cpu_type = TYPE_SH7750R_CPU;
+    mc->deprecation_reason = "old and unmaintained";
 }
 
 DEFINE_MACHINE("shix", shix_machine_init)