Move two members out of MIRGraph::temp_::ssa.

It turns out they are used outside the SSA transformation
by the x86 back-end.

This is a partial revert of
  https://android-review.googlesource.com/120571

Change-Id: Ia5cb2988ab0625d8519901124bd4fc184d5f0886
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index 23bdd87..af97f51 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -1317,6 +1317,9 @@
   CompilationUnit* const cu_;
   ArenaVector<int> ssa_base_vregs_;
   ArenaVector<int> ssa_subscripts_;
+  // Map original Dalvik virtual reg i to the current SSA name.
+  int* vreg_to_ssa_map_;            // length == method->registers_size
+  int* ssa_last_defs_;              // length == method->registers_size
   ArenaBitVector* is_constant_v_;   // length == num_ssa_reg
   int* constant_values_;            // length == num_ssa_reg
   // Use counts of ssa names.
@@ -1369,9 +1372,6 @@
       size_t num_vregs;
       ArenaBitVector* work_live_vregs;
       ArenaBitVector** def_block_matrix;  // num_vregs x num_blocks_.
-      // Map original Dalvik virtual reg i to the current SSA name.
-      int* vreg_to_ssa_map_;            // length == method->registers_size
-      int* ssa_last_defs_;              // length == method->registers_size
     } ssa;
     // Global value numbering.
     struct {