ART: Move oat_data_flow_attributes_ to private and put an API

The oat_data_flow_attributes had no checking mechanism to ensure bound
 correctness.

This fix handles this and also offers two functions to retrieve the
 attributes: using the MIR and DecodedInstruction.

Change-Id: Ib4f1f749efb923a803d364a4eea83a174527a644
Signed-Off-By: Jean Christophe Beyler <jean.christophe.beyler@intel.com>
diff --git a/compiler/dex/quick/mir_to_lir.cc b/compiler/dex/quick/mir_to_lir.cc
index 6c5279e..107987e 100644
--- a/compiler/dex/quick/mir_to_lir.cc
+++ b/compiler/dex/quick/mir_to_lir.cc
@@ -286,7 +286,7 @@
   // Prep Src and Dest locations.
   int next_sreg = 0;
   int next_loc = 0;
-  uint64_t attrs = mir_graph_->oat_data_flow_attributes_[opcode];
+  uint64_t attrs = MIRGraph::GetDataFlowAttributes(opcode);
   rl_src[0] = rl_src[1] = rl_src[2] = mir_graph_->GetBadLoc();
   if (attrs & DF_UA) {
     if (attrs & DF_A_WIDE) {