Match SelectionDAG logic for enabling movt.

Darwin doesn't do static, and ELF targets only support static.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147740 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 9c78483..95e535d 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -2166,7 +2166,8 @@
   MachineFunction &MF = DAG.getMachineFunction();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
 
-  // FIXME: Enable this for static codegen when tool issues are fixed.
+  // FIXME: Enable this for static codegen when tool issues are fixed.  Also
+  // update ARMFastISel::ARMMaterializeGV.
   if (Subtarget->useMovt() && RelocM != Reloc::Static) {
     ++NumMovwMovt;
     // FIXME: Once remat is capable of dealing with instructions with register