TargetMachine: Merge TargetMachine and LLVMTargetMachine

Merge LLVMTargetMachine into TargetMachine.

- There is no in-tree target anymore that just implements TargetMachine
  but not LLVMTargetMachine.
- It should still be possible to stub out all the various functions in
  case a target does not want to use lib/CodeGen
- This simplifies the code and avoids methods ending up in the wrong
  interface.

Differential Revision: https://reviews.llvm.org/D38489

llvm-svn: 315633
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
index aa76a96..d3f24c9 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
@@ -143,7 +143,7 @@
                                            Optional<Reloc::Model> RM,
                                            Optional<CodeModel::Model> CM,
                                            CodeGenOpt::Level OL, bool JIT)
-    : LLVMTargetMachine(
+    : TargetMachine(
           T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
           getEffectiveRelocModel(RM),
           getEffectiveCodeModel(CM, getEffectiveRelocModel(RM), JIT), OL),