Remove the use of TargetMachine from PPCJITInfo and replace with
the subtarget. Also remove unnecessary argument to the constructor
at the same time, we already have access via the subtarget.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210844 91177308-0d34-0410-b5e6-96231b3b80d8