tools: Fix vshControl declaration and initialization

tools: Fix vshControl declaration and initialization

Both virsh and virt-admin have vshControl typed variables and
also pointers to these variables. In both cases these are
declared on a single line. Do the following:

  1) break declaration into two lines,
  2) use struct zero initializer for vshControl and
     virshControl/vshAdmControl structs,
  3) drop explicit memset(.., 0, ...) ;

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Claudio Fontana <cfontana@suse.de>