scripts/tracetool: Use void pointer for vcpu

scripts/tracetool: Use void pointer for vcpu

dtrace on macOS complains that CPUState * is used for a few probes:

  dtrace: failed to compile script trace-dtrace-root.dtrace: line 130: syntax error near "CPUState"

A comment in scripts/tracetool/__init__.py mentions that:

  We only want to allow standard C types or fixed sized
  integer types. We don't want QEMU specific types
  as we can't assume trace backends can resolve all the
  typedefs

Fixes: 3d211d9f4dbee ("trace: Add 'vcpu' event property to trace guest vCPU")
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Message-id: 20200717093517.73397-3-r.bolshakov@yadro.com
Cc: Cameron Esfahani <dirty@apple.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>