[Bug driver/80271] Support environment variable CLICOLOR_FORCE to enable -fdiagnostics-color

[kilobyte at angband dot pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80271

Adam Borowski <kilobyte at angband dot pl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kilobyte at angband dot pl

--- Comment #6 from Adam Borowski <kilobyte at angband dot pl> ---
Created attachment 44260
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44260&action=edit
patch for CLICOLOR_FORCE

So, here's a patch.