Log Message:
cmake: update to 3.12.1

Changes in 3.12.1 since 3.12.0:
- CSharp: Set CMAKE_CSharp_COMPILER_LOADED variable when language is enabled
- UseSWIG: Use CSharp language only if it is enabled
- Help: Add explicit <PackageName>_ROOT variable documentation
- Tests: Add case showing CMP0048 warning on injected project command
- project: Do not issue CMP0048 warnings on injected call
- CPack: Restore support for 0-valued version components
- FindCUDA/select_compute_arch: Restore two-component CUDA_VERSION
- GoogleTest: Ensure policy settings allow use of IN_LIST
- FindTCL: Add support for version 8.7
- FindPython*: fix erroneous behavior on multiple 'find_package' calls
- UseSWIG: restore legacy behavior for SWIG_MODULE_<name>_EXTRA_FLAGS