Rewrite the attribute hashing algorithm to use the type of the value
pointed to by the attribute, rather than the form as a first
step to determining how to hash the values. No functional change
intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203044 91177308-0d34-0410-b5e6-96231b3b80d8