remove the SelectSectionForMachineConst hook, replacing it with

remove the SelectSectionForMachineConst hook, replacing it with
a new getSectionForMergableConstant hook.  This removes one dependence
of TAI on Type, and provides the hook with enough info to make the
right decision based on whether the global has relocations etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76705 91177308-0d34-0410-b5e6-96231b3b80d8