Revert "disable row mt test"

Revert "disable row mt test"

This reverts commit 6d6cc17dc852a216395611bf651e57c19c95b9c4.

Reason for revert:
This has not been reproduced on hardware. There is a strange
libc bug which may account for the behavior on arm because
the environment qemu is using is somewhat old. See discussion
on the webm bug.

To work around the failures in the nightly test the jenkins
job has been switched to use the hardfloat compiler and qemu
environment. Even though this is the same version, it has
not shown the hanging behavior.

Original change's description:
> disable row mt test
>
> deadlock is being investigated in attached bug.
>
> BUG=webm:1626
>
> Change-Id: Ia6d7020b8b1d274433aa89f36c9ed5b9facc5808

Bug: webm:1626
Change-Id: I104a82696a4c90bfbadfd39407c073adce73af0d