We detect errors in several places.  One reports with g_error(), which
calls abort(), the others report with g_critical().  Three of them
exit(), three return false.

Always report with g_critical(), and return false.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: NLuiz Capitulino <lcapitulino@redhat.com>

*minor fix-up of commit msg
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>