buildhistory: use bb.utils.mkdirhier instead of os.makedirs

buildhistory: use bb.utils.mkdirhier instead of os.makedirs

* Multiple do_fetch[prefunc] can happen at the same time and
  if not os.path.exists(pkghistdir):
    os.makedirs(pkghistdir)
  isn't safe
* Use bb.utils.mkdirhier which doesn't raise error when directory exists

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>