sys-devel/binutils: Disable gold testsuite in stable candidate.

sys-devel/binutils: Disable gold testsuite in stable candidate.

The testsuite always fails. The failures are most likely Gentoo-specific
and still need a fix sometime. Meanwhile, let's give the entire testsuite
a chance to succeed (as in previous stabilizations).

Bug: https://bugs.gentoo.org/681682
Bug: https://bugs.gentoo.org/662362
Bug: https://bugs.gentoo.org/667894
Bug: https://bugs.gentoo.org/677914
Package-Manager: Portage-2.3.62, Repoman-2.3.12
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>