hw/m68k/q800.c: Make the GLUE chip an actual QOM device

hw/m68k/q800.c: Make the GLUE chip an actual QOM device

The handling of the GLUE (General Logic Unit) device is
currently open-coded. Make this into a proper QOM device.

This minor piece of modernisation gets rid of the free
floating qemu_irq array 'pic', which Coverity points out
is technically leaked when we exit the machine init function.
(The replacement glue device is not leaked because it gets
added to the sysbus, so it's accessible via that.)

Fixes: Coverity CID 1421883
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20201106235109.7066-3-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>