qerror_report_err() is a transitional interface to help with
converting existing monitor commands to QMP.  It should not be used
elsewhere.

The only remaining user in qemu-option.c is qemu_opts_parse().  Is it
used in QMP context?  If not, we can simply replace
qerror_report_err() by error_report_err().

The uses in qemu-img.c, qemu-io.c, qemu-nbd.c and under tests/ are
clearly not in QMP context.

The uses in vl.c aren't either, because the only QMP command handlers
there are qmp_query_status() and qmp_query_machines(), and they don't
call it.

Remaining uses:

* drive_def(): Command line -drive and such, HMP drive_add and pci_add

* hmp_chardev_add(): HMP chardev-add

* monitor_parse_command(): HMP core

* tmp_config_parse(): Command line -tpmdev

* net_host_device_add(): HMP host_net_add

* net_client_parse(): Command line -net and -netdev

* qemu_global_option(): Command line -global

* vnc_parse_func(): Command line -display, -vnc, default display, HMP
  change, QMP change.  Bummer.

* qemu_pci_hot_add_nic(): HMP pci_add

* usb_net_init(): Command line -usbdevice, HMP usb_add

Propagate errors through qemu_opts_parse().  Create a convenience
function qemu_opts_parse_noisily() that passes errors to
error_report_err().  Switch all non-QMP users outside tests to it.

That leaves vnc_parse_func().  Propagate errors through it.  Since I'm
touching it anyway, rename it to vnc_parse().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NLuiz Capitulino <lcapitulino@redhat.com>