My machine has both an intel and an nvidia vga card, and both support
opencl. When the intel one is not blacklisted, then
CppunitTest_sc_opencl_test's testFinancialXirrFormula() fails all the
time. With the blacklist the nvidia one is used during the tests and
the test passes just fine.

Change-Id: Ib539faebcaf51867bdc1923f896219afcf92b5ef
(cherry picked from commit 452b1872)
Reviewed-on: https://gerrit.libreoffice.org/18307Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>