xl: Do not leak events when a domain exits.

xl: Do not leak events when a domain exits.

The goto in both of these places misses the event free which would
normally clean up.

==8655== 80 bytes in 1 blocks are definitely lost in loss record 1 of 1
==8655==    at 0x4024370: calloc (vg_replace_malloc.c:593)
==8655==    by 0x406EAAE: libxl__zalloc (libxl_internal.c:83)
==8655==    by 0x4078173: libxl__event_new (libxl_event.c:1167)
==8655==    by 0x4056373: domain_death_occurred (libxl.c:958)
==8655==    by 0x4058D06: domain_death_xswatch_callback (libxl.c:1038)
==8655==    by 0x4078EB5: watchfd_callback (libxl_event.c:458)
==8655==    by 0x407839E: afterpoll_internal (libxl_event.c:949)
==8655==    by 0x4079142: eventloop_iteration (libxl_event.c:1371)
==8655==    by 0x40799BB: libxl_event_wait (libxl_event.c:1396)
==8655==    by 0x805CC67: create_domain (xl_cmdimpl.c:1698)
==8655==    by 0x805E001: main_create (xl_cmdimpl.c:3986)
==8655==    by 0x804D43D: main (xl.c:285)

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>