[CMake] Nina Generator on Windows generates too long link cmd lines

[Bill Hoffman]

We are you using the linker support for response files?  I thought ninja 
was handling this with its own response files?


rspfile, rspfile_content
rule link
   command = link.exe /OUT$out [usual link flags here] @$out.rsp
   rspfile = $out.rsp
   rspfile_content = $in

Seems like command could be anything at all.

    command = foobar $out bunch of stuff  @$out.rsp

Also, perhaps we should move this to the cmake-developers list?  Are you 
both on that list?

-Bill