Use llvm::array_lengthof to replace sizeof(array)/sizeof(array[0]).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186301 91177308-0d34-0410-b5e6-96231b3b80d8
Revert part of 186302 to fix buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186303 91177308-0d34-0410-b5e6-96231b3b80d8