[CMake] Watcom Support

[Bill Hoffman]

J Decker wrote:
> but then, for every project that already exists, it won't build
> correctly using watcom, because the options just aren't set in the
> generator, or 3 more flavors of generators aren't added to support
> static library, executlable and dynamic library with correct compile
> time options.
> 

It should go in Modules/Platform/Windows-wcl386.cmake.

Just set these:
CMAKE_EXE_LINKER_FLAGS_DEBUG_INIT
CMAKE_SHARED_LINKER_FLAGS_INIT
CMAKE_SHARED_LINKER_FLAGS_DEBUG_INIT


See Windows-cl.cmake for an example, you will also want to set 
RELWITHDEBINFO to have the same flag.  If you can verify this works, I 
will merge into git master for CMake.

-Bill