[CMake] [ANNOUNCE] CMake Issue Tracker Moved

[Brad King]

Hi Folks,

CMake issue tracking is now hosted on Kitware's GitLab instance:

  https://gitlab.kitware.com/cmake/cmake/issues

The old mantis issue tracker will remain available as a read-only
reference.  All CMake issues from that tracker have been migrated
to the new CMake Issues page with their original numbers intact
and links back to the original mantis pages in their descriptions.
Further discussion of any issue should take place on its new page.

-Brad