Updated tag to be used by tcwg-regression-detection job.

This revision of tcwg-regression includes checks to the new toolchain
layout (without runtest, and with gdbserver in the sysroot path).

The tests pass when re-building an old release with a new ABE version,
but an old release would not contain fixes for other tests included in
tcwg-regression in the tag we used so far in tcwg-regression-detection
job (tag ok-for-regtest-with-gcc-linaro-6.2-2016.11).

Using this new version of tcwg-regression tests in
tcwg-regression-detection implies updating the release version rebuilt
in tcwg-regression-detection.