Revert "TargetMachine: Merge TargetMachine and LLVMTargetMachine"

Reverting to investigate layering effects of MCJIT not linking
libCodeGen but using TargetMachine::getNameWithPrefix() breaking the
lldb bots.

This reverts commit r315633.

llvm-svn: 315637
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
index 179971b..6199ffd 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -109,9 +109,9 @@
                                      Optional<CodeModel::Model> CM,
                                      CodeGenOpt::Level OL, bool JIT,
                                      bool isLittle)
-    : TargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
-                    CPU, FS, Options, getEffectiveRelocModel(JIT, RM),
-                    getEffectiveCodeModel(CM), OL),
+    : LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
+                        CPU, FS, Options, getEffectiveRelocModel(JIT, RM),
+                        getEffectiveCodeModel(CM), OL),
       isLittle(isLittle), TLOF(llvm::make_unique<MipsTargetObjectFile>()),
       ABI(MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions)),
       Subtarget(nullptr), DefaultSubtarget(TT, CPU, FS, isLittle, *this,