xen-access: minor fixes

xen-access: minor fixes

Only copy the VCPU_PAUSED flag to the response. Copy the entire mem_access
struct which is useful and easily forgotten when also testing the emulate
response flags. Turn off singlestepping on the vCPUs once we are done
processing all events, as we might have turned on singlestep there and leave
the VM in an undesirable state.

Signed-off-by: Tamas K Lengyel <tlengyel@novetta.com>
Cc: Razvan Cojocaru <rcojocaru@bitdefender.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com>