Such exotic systems as OS X in a few versions, BSD and four flavors of Windows? (cygwin, mingw, MSVC, msys) Add a few flavors of Linux and perhaps even Android

Such exotic systems as OS X in a few versions, BSD and four flavors of Windows? (cygwin, mingw, MSVC, msys) Add a few flavors of Linux and perhaps even Android (all 3 current targets) on top. That with cross compilation. Even Cmake lacks some useful portability tools to handle this... Though Autotools have major problems too.