The ctest_configure command already reads the CTEST_CMAKE_GENERATOR
variable to get the value for the cmake -G option. Read new variable
CTEST_CMAKE_GENERATOR_TOOLSET for -T.
The "ctest --build-and-test" mode already has "--build-generator" to
specify the -G option to CMake. Add a "--build-generator-toolset" option
to specify the -T value.
This converts the CMake license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the CMake copyright to
cover the full development time range.