CMake: set Google Test options properly

If the used CMake version is recent enough to support the necessary
policy CMP0077, set INSTALL_GTEST using normal variables instead of
cache variables. We never want to allow Google Test to add to the
install target, so we should not allow a user to interfere with this.

In addition, we set BUILD_GMOCK=OFF (and the necessary BUILD_GTEST=ON
for Google Test 1.8.0), as our current tests do not require Google Mock.

0 files changed, 0 insertions, 0 deletions