R600: Make ShaderType private

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212896 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Use range for and fix missing consts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212897 91177308-0d34-0410-b5e6-96231b3b80d8