[cmake] Start making LLVM_LIBDIR_SUFFIX effective by adding it to

*numerous* places where it was missing in the CMake build. The primary
change here is that the suffix is now actually used for all of the lib
directories in the LLVM project's CMake. The various subprojects still
need similar treatment.

This is the first of a series of commits to try to make LLVM's cmake
effective in a multilib Linux installation. I don't think many people
are seriously using this variable so I'm hoping the fallout will be
minimal. A somewhat unfortunate consequence of the nature of these
commits is that until I land all of them, they will in part make the
brokenness of our multilib support more apparant. At the end, things
should actually work.

llvm-svn: 224919