External checkpoints could be created with snapshot-create, but
without libvirt supplying a default name for the memory file,
it is essential to add a new argument to snapshot-create-as to
allow the user to choose the memory file name. This adds the
option --memspec [file=]name[,snapshot=type], where type can
be none, internal, or external. For an example,
virsh snapshot-create-as $dom --memspec /path/to/file
is the shortest possible command line for creating an external
checkpoint, named after the current timestamp.
* tools/virsh-snapshot.c (vshParseSnapshotMemspec): New function.
(cmdSnapshotCreateAs): Use it.
* tests/virsh-optparse (test_url): Test it.
* tools/virsh.pod (snapshot-create-as): Document it.
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