Adding new *.replies files for qemucapabilitiestest or updating the
files when libvirt adds an additional QMP command into the probing
process is quite painful. The goal of the new qemucapsprobe command is
to make this process as easy as

    tests/qemucapsprobe /path/to/qemu/binary >caps.replies
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>