Since 3.19, CMake generates a deprecation warning when using a minimum
version less than 2.8.12. This eliminates those warnings generated
during tests, which are typically hidden from the user and developer but
are being generated nonetheless.
These tests were not running properly on Visual Studio or
Xcode dashboards before this commit because of the "Debug"
or "Release" sub-directory. The scripts already have
CMAKE_CPACK_COMMAND since the correct CMake executable is
used to run the scripts, so just use that, rather than
passing down an incorrect path to the CPack executable.