[CMake][VS][XCode] Restruct the output directory layout more comfortable, ${BINARY_DIR}/${BUILD_MODE}/(bin|lib)

We have been seeing nasty directory layout with CMake multiconfig, such as,
  bin/Release/clang.exe
  lib/clang/3.x/...
  lib/Release/clang/3.x/.. (duplicated)

Move the layout similar to autoconf's;
  Release/bin/clang.exe
  Release/lib/clang/3.x/...

Checked on Visual Studio 10. Could you guys please confirm my change on XCode(and other multiconfig builders)?

Note: Don't set variables CMAKE_*_OUTPUT_DIRECTORY any more, or a certain builder, for eaxample, msbuild.exe, would be confused.
llvm-svn: 198205