tar: Add ptest support

tar: Add ptest support

Add ptest support for tar.

It contains two parts.

One part is a backport for
  http://cgit.openembedded.org/openembedded-core/commit/?h=master-next&id=878e154181e5e8d18e3605f0989bebf4aec1c6e1
It should be deleted after yocto version up.

Another part is changing formate of the result of "ptest-runner tar"
Because some cases have same name, adding a case number can better
locate incorrect case.
A sample:
  PASS: tar version  -->  PASS:   1: tar version

SPEC-4753

Signed-off-by: Qiu Tingting <qiutt@fujitsu.com>
Change-Id: I878bdf1693f0e71c1ba33642cd4ff70977e125f9