Python: Use correct ptid in btrace recording

The user would always get the instruction_history and function_call_history
objects of the current thread, not the thread for which the gdb.Record object
was created.

The attached testcase fails without this patch and passes with the patch.

gdb/python/py-record.c

@@ -18,26 +18,11 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
-#include "inferior.h"
-#include "record.h"
-#include "python-internal.h"
+#include "py-record.h"
 #include "py-record-btrace.h"
 #include "py-record-full.h"
 #include "target.h"
 
-/* Python Record object.  */
-
-typedef struct
-{
-  PyObject_HEAD
-
-  /* The ptid this object refers to.  */
-  ptid_t ptid;
-
-  /* The current recording method.  */
-  enum record_method method;
-} recpy_record_object;
-
 /* Python Record type.  */
 
 static PyTypeObject recpy_record_type = {