Keep track of guest paused state after disk IO / watchdog events

Keep track of guest paused state after disk IO / watchdog events

When a watchdog/IO error occurs, one of the possible actions that
QEMU might take is to pause the guest. In this scenario libvirt
needs to update its internal state for the VM, and emit a
lifecycle event:

  VIR_DOMAIN_EVENT_SUSPENDED

with a detail being one of:

  VIR_DOMAIN_EVENT_SUSPENDED_IOERROR
  VIR_DOMAIN_EVENT_SUSPENDED_WATCHDOG

To future proof against possible QEMU support for multiple monitor
consoles, this patch also hooks into the 'STOPPED' event in QEMU
and emits a generic VIR_DOMAIN_EVENT_SUSPENDED_PAUSED event

* include/libvirt/libvirt.h.in: Add VIR_DOMAIN_EVENT_SUSPENDED_IOERROR
* src/qemu/qemu_driver.c: Update VM state to paused when IO error
  or watchdog events occurrs
* src/qemu/qemu_monitor_json.c: Fix typo in disk IO event name