qerror: drop qerror_abort()

qerror: drop qerror_abort()

qerror_abort() depends on the 'file', 'func' and 'linenr' members of
QError. However, these members are going to be dropped by the next
commit, so let's drop qerror_abort() in favor of printing an error
message to stderr plus a call to abort().

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>