No need to store the TargetMachine variable in this class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182317 91177308-0d34-0410-b5e6-96231b3b80d8
The DWARF EH pass doesn't need the TargetMachine, only the TargetLoweringBase like the other EH passes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182321 91177308-0d34-0410-b5e6-96231b3b80d8