qemu: adjust QMP naming to avoid non-unique truncation

[egernst]

The full name of the QMP monitor and control sockets was well beyond the 107 character limit, resulting in the full name to be truncated during creation. As a result, only a single socket was created.

Instead of creating a socket at

/-, create it at /-, keeping as much of the unique socket name as feasible. Also, to reduce truncation the ".sock" from the socket names were removed. Fixes #552 Signed-off-by: Eric Ernst

[egernst]

@sboeuf -- not ideal, but much safer, imo.

[sboeuf]

@egernst agreed

[sboeuf]

LGTM

[sameo]

LGTM