Rework the logic for setting the TargetName. This appears to
be shorter and identical in goal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211845 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unnecessary caching of the TargetMachine on NVPTXFrameLowering.
Adjust the constructor accordingly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211846 91177308-0d34-0410-b5e6-96231b3b80d8
Move the constructor for NVPTXFrameLowering into the implementation
file in preparation for the subtarget move.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211847 91177308-0d34-0410-b5e6-96231b3b80d8