Without this, assertion failures can make life hard for users and those
trying to help them.
v2:
* Change commit log wording slightly to "can make life hard", since
apparently e.g. logind can alleviate that somewhat.
* Set default handler for SIGABRT in
hw/xfree86/common/xf86Init.c:InstallSignalHandlers() and
hw/xquartz/quartz.c:QuartzInitOutput() (Eric Anholt)
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>