title: How do I enable link time optimization (LTO) with CMake?
body: <p>I have the most recent cmake build and trying all build configurations (Debug, MinSizeRel, RelWithDebugInfo, Release, General) I see nowhere (text search) in generated makefiles the string <code>-lto</code>, so or the functionality is still not present, or it requires manual intervertion (in that case a text search for LTO or Link time optimization) over the documentation gives no result, so I see nowhere in official documentation a way to enable LTO.</p>
  
  <p>Is there any way to enable LTO "globally" (for all compilers) without specifying manually flags that could be at worst supported only by GCC?</p>