cmake/UnitTests: Remove duplicated else
cmake/UnitTests: Remove duplicated else

Suggested-by: Dzenan Zukic <052569de452143a9cb2f66e47328d18a08e2500e@kitware.com>

python-cmake-buildsystem/python-cmake-buildsystem,davidsansome/python-cmake-buildsystem,adrianbroher/python-cmake-buildsystem