Add the majority of the vector machien value types we expect to support,

Add the majority of the vector machien value types we expect to support,
and make a few changes to the legalization machinery to support more than
16 types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24511 91177308-0d34-0410-b5e6-96231b3b80d8