[CMake] ninja under windows

[Gonzalo Garramuño]

I compiled Ninja on cygwin from git.  That now works fine it seems.
I am trying to compile for msvc.  However, when cmake runs, I get:

[1/123] Building CXX object 
'libACESclip\CMakeFiles\ACESclip.dir\src\ACESclipWriter.cpp.obj'ninja: 
fatal: unknown deps type 'msvc'

$ ninja --version
1.6.0.git

Is compiling under the microsoft compiler not an option for ninja files 
( I can compile with NMake Makefiles just fine in the same project ).