Move TargetFrameLowering.h to CodeGen where it's implemented

This header already includes a CodeGen header and is implemented in
lib/CodeGen, so move the header there to match.

This fixes a link error with modular codegeneration builds - where a
header and its implementation are circularly dependent and so need to be
in the same library, not split between two like this.

llvm-svn: 317379
diff --git a/llvm/lib/CodeGen/PatchableFunction.cpp b/llvm/lib/CodeGen/PatchableFunction.cpp
index 513e827..b0424e7 100644
--- a/llvm/lib/CodeGen/PatchableFunction.cpp
+++ b/llvm/lib/CodeGen/PatchableFunction.cpp
@@ -16,7 +16,7 @@
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/Passes.h"
-#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/CodeGen/TargetFrameLowering.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"