Attribute: Make hashes match when looking up AttributeImpls.

This isn't optimal either but fixes a massive compile time regression from the
attribute uniquing work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171624 91177308-0d34-0410-b5e6-96231b3b80d8
Funnel the actual TargetTransformInfo pass from the SelectionDAGISel
pass into the SelectionDAG itself rather than snooping on the
implementation of that pass as exposed by the TargetMachine. This
removes the last direct client of the ScalarTargetTransformInfo class
outside of the TTI pass implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171625 91177308-0d34-0410-b5e6-96231b3b80d8